Pipe Support Span (Spacing) | Pipe Support Spacing (Span) Chart/Table

Written by Anup Kumar Dey in Piping Stress Basics,Piping Supports

Pipe support spans play a crucial role in maintaining the longevity, efficiency, and safety of aboveground piping and pipeline systems. Pipe support span is also known as pipe support spacing. A proper pipe support span not only reduces the pipe supporting problems but also adequately supports pipes at regular intervals to reduce failures associated with improper supporting. In this comprehensive guide, we will discuss the intricacies of pipe support spans, covering design considerations, factors on which it depends, best practices, and pipe support spacing charts based on different codes and standards.

A. What is a Pipe Support Span?

Pipe Support Span is defined as the optimum distance between two consecutive pipe supports to avoid excessive stress, sagging, bending, vibration, or failure of the piping or pipeline system in extreme cases. It ensures that the piping system remains securely in place throughout operation. Adequate pipe support spacing is synonymous with

Structural Integrity
Reduced Maintenance
Safety
Operational Efficiency

We all know that while routing aboveground piping or pipeline from one part or equipment to another we have to support the pipe at some definite spans. A properly designed pipe support span helps the piping design personnel to support pipes at regular spacings, thus reducing his work for unnecessary calculations. Pipe Support Span is also known as Pipe Support Spacing. Refer to Fig. 1 which defines the pipe support span for a pipeline system.

B. Factors on Which Pipe Support Span Depends

Various factors influence the pipe support span. In the following section, we will discuss 11 such important criteria that dictate the Pipe support spacing.

1. Pipe Material:

Pipe Support spacing varies with pipe material, For non-metallic pipes, the support span is lower than metallic pipes of the same size. Even Stainless Steel pipes have lower pipe support spacing as compared to Carbon steel pipes.

2. Nominal Diameter of Pipe & Schedule:

With the increase in pipe diameter and schedule, the pipe support span increases. That is the reason you will find that a 10-inch pipe has more support span as compared to a 4-inch pipe support spacing.

3. Type of Fluid Service:

Piping support span varies with fluid service; Pipes carrying liquid service have less support span as compared to pipes carrying gaseous fluids. This means with an increase in the density of the flow medium pipe support spacing decreases.

4. Type and Thickness of Insulation Material:

With an increase in thickness and density of the pipe insulation material, pipe support spacing reduces. An increase in insulation density and thickness imposes more load on the parent pipe which needs to be supported by increasing the number of supports which means the pipe support span reduces.

5. Piping Configuration (Straight pipe and Pipe with elbows):

Pipe support spacing is dependent on the piping routing or geometry. A straight pipe has more support span as compared to pipes with directional changes. Because of this reason, to find out the span for piping including elbows, the straight pipe span is multiplied by a factor as shown in Fig. 2.

6. Locations of Valves and Rigid Bodies:

The presence of rigid bodies in a piping or pipeline system reduces the pipe support span. It is a general engineering practice to provide at least one support near rigid bodies like valves (Preferably to provide support on both sides of the valve).

7. Structural Availability for Supporting:

Available structures are normally used for supporting the pipe. So, the pipe span chart may be reduced in those places. Also, an increase in the number of supports distributes the piping loads on supports and increases the piping stiffness. So, if a structure is available, pipe supports are usually taken from those structures.

8. Vibrating or Pulsating lines:

For vibrating or pulsating lines pipe support span is reduced to avoid vibration tendency and to increase the natural frequency of the piping system. A reduction in pipe support spacing increases the system rigidity which reduces the tendency of pipe vibration.

9. Fluid Temperature:

With an increase in fluid temperature as the pipe material’s allowable stress value reduces, the pipe is supported in a nearby position, thus reducing the pipe support spacing.

10. Equipment Connection

Sometimes, the Pipe support span is determined considering various equipment connections that have the potential for vibration transfer from the equipment like reciprocating compressors and reciprocating pumps. For these pipes, the supporting span is reduced from the standard pipe support spacing.

11. Flow Induced Vibration Criteria

For lines with the flow-induced vibration susceptibility as high, the pipe support span is reduced to increase the natural frequency of the piping system so that the tendency of FIV failure is reduced.

**Fig. 1: Figure showing pipe support span**

C. Deciding Pipe Support Span

Pipe Support Span Length Depends On-

Bending Stress
Deflection
Indentation
Allowable Loads
Vibration Possibility and Natural Frequency of the piping system

1. Bending Stress

Bending is caused mainly due to two reasons:

Uniform Weight Load
Concentrated Weight Load

1.1 Uniform Weight Load

Own Weight Of Pipe
Insulation Weight
Weight of Fluid During operation
Weight of hydrostatic fluid During Hydro Test

1.2 Concentrated Load

Weight Of Valve, Flanges,
Strainer, specialty items, inline items, etc.

2. Deflection

Deflection (Δ) is defined as a relative displacement of the point from its original position.

The basic piping practice is to limit pipe deflection between supports to 1” or 1/2 the nominal pipe diameter, whichever is smaller.
The most important reason for limiting deflection is to make the pipe stiff enough, that is, of high enough natural frequency, to avoid a large amplitude response under any slight perturbing force. As a rough rule, for average piping, a natural frequency of 4 cycles per second will be found satisfactory. The natural frequency can be calculated by

3. Indentation

Where,

t=corroded Thickness of pipe Wall(mm)
S=0.67Sh(N/mm^2)
R=Radius of pipe (mm)
d=Bearing Length(mm)
b=Bearing width(mm)

4. Allowable Load at Support

Where,

P_a=Allowable Load at the Support point
t=effective local thickness (pipe wall +Reinforced Pad If Any)
R=outer radius of Pipe
b=Bearing length of pipe (along the axis) on the support structure

IF THE ACTUAL LOAD AT SUPPORT IS GREATER THAN THE ALLOWABLE LOAD GIVEN BY THE ABOVE FORMULA, A REINFORCEMENT PAD WILL BE REQUIRED.

5. Vibration Possibility

The support span for vibration-prone lines is reduced to make the system stiffer such that the pipe does not easily vibrate. The natural frequency of the system is usually maintained above 4 Hz as mentioned in clause C.2 above.

D. Pipe Support Span Chart

A pipe support span chart is a table or diagram that provides information on the maximum allowable span for different types of piping and support configurations. The span is the distance between two points where a pipe is supported, such as at two adjacent pipe hangers.

The purpose of a pipe support span chart is to help engineers and designers ensure that piping systems are properly supported to prevent sagging, bending, or other types of stress that could cause damage or failure. By referring to the span chart, designers can select the appropriate type and spacing of supports for a given piping configuration, based on the materials used, the size and weight of the pipes, the fluid being transported, and other factors.

Pipe support span charts may also include information on the recommended type of support for different piping materials, such as steel, copper, or plastic, as well as information on recommended hanger spacing, temperature limits, and other design considerations. Proper use of a pipe support span chart can help ensure that piping systems are safe, reliable, and long-lasting.

Normally project-specific Support Span is provided in tabular format for straight pipes that are known as a “Pipe Support Span Chart”. But for elbows or turns, the span is to be reduced by a factor as shown in the attached figure (Fig. 2). Readymade support spans for specific pipe diameters and thicknesses are available in the MSS code. For the Shell group of companies, the support span is provided in DEP in tabular format.

**Fig. 2: Factor to reduce support span depending on layout.**

1. Pipe Support Spacing Chart for Steel Piping as per MSS-SP-69

A pipe support span chart is a tabular chart giving a rough idea of supporting distance. These charts are normally mentioned in piping stress analysis project specifications. In the following image (Fig. 3) pipe support span chart from MSS SP-69 is reproduced as a sample.

**Fig. 3: Sample Piping Support Span Chart (Reference: MSS SP-69)**

2. Pipe Support Spacing Chart for Steel Piping Based on ASME B31.1

The pipe support span as per ASME B31.1 for Steel piping is provided below:

Pipe Support Span Based on ASME B31.1, Power Piping Code
NPS (Inches)	DN (mm)	Water/ Liquid Service (m)	Water/ Liquid Service (ft)	Steam, Gas, Air Service (m)	Steam, Gas, Air Service (ft)
1	25	2.1	7	2.7	9
2	50	3.0	10	4.0	13
3	80	3.7	12	4.6	15
4	100	4.3	14	5.2	17
6	150	5.2	17	6.4	21
8	200	5.8	19	7.3	24
12	300	7.0	23	9.1	30
16	400	8.2	27	10.7	35
20	500	9.1	30	11.9	39
24	600	9.8	32	12.8	42

Table 1: Pipe Support Spacing in ft and m as per ASME B31.1-Power Piping Code

General Notes for Table 1:

This support span is valid for horizontal straight runs of standard and heavier steel pipe at a maximum operating temperature of 750°F (400°C).
This support spacing chart does not apply in the presence of concentrated loads between supports, such as flanges, valves, and specialties.
The pipe support spacing is based on a fixed beam support with a bending stress limiting to 2,300 psi (15.86 MPa) and insulated pipe filled with water or the equivalent weight of steel pipe for steam, gas, or air service, and the pitch of the line is such that a sag of 0.1 in. (2.5 mm) between supports is permissible.

3. Pipe Support Span Chart as per ASME B31.3

Process piping code ASME B31.3 does not provide any span chart for steel piping systems. Users usually develop their pipe support spacing table considering parameters like allowed stress, deflection, etc. A typical pipe support span for process piping for carbon steel and stainless steel pipe material is provided below (Reference: Shell DEP) in Table 2 and Table 3.

3.1 Pipe Support Span for Carbon Steel

Typical Support Span for carbon steel and heavy wall stainless steel
	Vapour service		Liquid service
Pipe size	Bare	Insulated	Bare	Insulated
DN 15 (NPS ½)	900 mm (3 ft)	800 mm (2 ½ ft)	900 mm (3 ft)	800 mm (2 ½ ft)
DN 20 (NPS ¾)	1400 mm (4 ½ ft)	1200 mm (3.9 ft)	1400 mm (4 ½ ft)	1200 mm (3.9 ft)
DN 25 (NPS 1)	3600 mm (11.8 ft)	2300 mm (7.5 ft)	3450 mm (11.3 ft)	2250 mm (7.3 ft)
DN 40 (NPS 1 ½)	3600 mm (11.8 ft)	3000 mm (9.8 ft)	3450 mm (11.3 ft)	2800 mm (9.1 ft)
DN 50 (NPS 2)	3600 mm (11.8 ft)	3450 mm (11.3 ft)	3450 mm (11.3 ft)	3300 mm (10.8 ft)
DN 80 (NPS 3)	6550 mm (21.4 ft)	4600 mm (15 ft)	5450 mm (17.8 ft)	4200 mm (13.7 ft)
DN 100 (NPS 4)	7500 mm (24.6 ft)	5550 mm (18.2 ft)	6100 mm (20 ft)	4900 mm (16 ft)
DN 150 (NPS 6)	9150 mm (30 ft)	6800 mm (22.3 ft)	7100 mm (23.2 ft)	5800 mm (19 ft)
DN 200 (NPS 8)	10500 mm (34.4 ft)	8050 mm (26.4 ft)	7950 mm (26 ft)	6700 mm (21.9 ft)
DN 250 (NPS 10)	11800 mm (38.7 ft)	9050 mm (29.6 ft)	8700 mm (28.5 ft)	7400 mm (24.2 ft)
DN 300 (NPS 12)	12900 mm (42.3 ft)	9800 mm (32.1 ft)	9150 mm (30 ft)	7800 mm (25.5 ft)
DN 350 (NPS 14)	15150 mm (49.7 ft)	11850 mm (38.8 ft)	10850 mm (35.5 ft)	9300 mm (30.5 ft)
DN 400 (NPS 16)	16250 mm (53.3 ft)	12850 mm (42.1 ft)	11200 mm (36.7 ft)	9750 mm (31.9 ft)
DN 450 (NPS 18)	17250 mm (56.5 ft)	13750 mm (45.1 ft)	11500 mm (37.7 ft)	10150 mm (33.3 ft)
DN 500 (NPS 20)	18200 mm (59.7 ft)	14450 mm (47.4 ft)	11750 mm (38.5 ft)	10400 mm (34.1 ft)
DN 600 (NPS 24)	18950 mm (62.1 ft)	16050 mm (52.6 ft)	12150 mm (39.8 ft)	10950 mm (35.9 ft)
DN 750 (NPS 30)	21000 mm (68.9 ft)	17500 mm (57.4 ft)	13100 mm (43 ft)	11500 mm (37.7 ft)
DN 900 (NPS 36)	22700 mm (74.5 ft)	18500 mm (60.7 ft)	13700 mm (45 ft)	12500 mm (41 ft)
DN 1050 (NPS 42)	23400 mm (76.8 ft)	19500 mm (64 ft)	14300 mm (47 ft)	13000 mm (42.6 ft)
DN 1200 (NPS 48)	25000 mm (82 ft)	20500 mm (67.2 ft)	14600 mm (48 ft)	13400 mm (44 ft)

Table 2: Pipe Support Span for Carbon Steel and Heavy Wall Stainless Steel

3.2 Pipe Support Span for Stainless Steel

Maximum spans for stainless steel, schedule 10S
	Vapour service		Liquid service
Pipe size	Bare	Insulated	Bare	Insulated
DN 25 (NPS 1)	2200 mm (7.2 ft)	1800 mm (5.9 ft)	2100 mm (6.8 ft)	1800 mm (5.9 ft)
DN 40 (NPS 1 ½)	2800 mm (9.1 ft)	2500 mm (8.2 ft)	2400 mm (7.8 ft)	2500 mm (8.2 ft)
DN 50 (NPS 2)	2800 mm (9.1 ft)	2600 mm (8.5 ft)	2700 mm (8.8 ft)	2600 mm (8.5 ft)
DN 80 (NPS 3)	6400 mm (21 ft)	4050 mm (13.2 ft)	4950 mm (16.2 ft)	3500 mm (11.4 ft)
DN 100 (NPS 4)	6400 mm (21 ft)	4800 mm (15.7 ft)	5300 mm (17.3 ft)	4000 mm (13.1 ft)
DN 150 (NPS 6)	9400 mm (30.8 ft)	5750 mm (18.8 ft)	5950 mm (19.5 ft)	4600 mm (15 ft)
DN 200 (NPS 8)	10750 mm (35.2 ft)	6800 mm (22.3 ft)	6450 mm (21.1 ft)	5200 mm (17 ft)
DN 250 (NPS 10)	10750 mm (35.2 ft)	7600 mm (24.9 ft)	6950 mm (22.8 ft)	5650 mm (18.5 ft)
DN 300 (NPS 12)	10750 mm (35.2 ft)	8250 mm (27 ft)	7350 mm (24.1 ft)	6050 mm (19.8 ft)
DN 350 (NPS 14)	10750 mm (35.2 ft)	8700 mm (28.5 ft)	7600 mm (24.9 ft)	6300 mm (20.6 ft)
DN 400 (NPS 16)	11000 mm (36 ft)	9450 mm (31 ft)	7750 mm (25.4 ft)	6550 mm (21.4 ft)
DN 450 (NPS 18)	11000 mm (36 ft)	9700 mm (31.8 ft)	7850 mm (25.7 ft)	6750 mm (22.1 ft)
DN 500 (NPS 20)	11500 mm (37.7 ft)	10500 mm (34.5 ft)	8400 mm (27.5 ft)	7300 mm (23.9 ft)
DN 600 (NPS 24)	12000 mm (39.3 ft)	11000 mm (36 ft)	9050 mm (29.6 ft)	8050 mm (26.4 ft)
DN 750 (NPS 30)	14000 mm (45.9 ft)	13000 mm (42.6 ft)	10500 mm (34.5 ft)	9500 mm (31.2 ft)
DN 900 (NPS 36)	16000 mm (52.5 ft)	15000 mm (49.2 ft)	11500 mm (37.7 ft)	10500 mm (34.5 ft)
DN 1050 (NPS 42)	18000 mm (59 ft)	16500 mm (54 ft)	12500 mm (41 ft)	11500 mm (37.7 ft)
DN 1200 (NPS 48)	20000 mm (65.6 ft)	17300 mm (56.8 ft)	13500 mm (44.3 ft)	12500 mm (41 ft)

Table 3: Maximum Pipe Support Spans for Stainless Steel, Schedule 10S Pipe

E. HDPE Pipe Support Span

The maximum allowable span for HDPE pipes will depend on various factors, such as the pipe size, wall thickness, and temperature of the fluid being transported. In general, HDPE pipes require more support than steel pipes due to their flexibility and low modulus of elasticity.

The Plastics Pipe Institute (PPI) provides guidelines for designing supports for HDPE pipes, which includes recommendations for maximum allowable span. According to PPI, the maximum allowable span for HDPE pipes should not exceed the following:

4 feet for 1-inch diameter pipes
5 feet for 1.25-inch diameter pipes
6 feet for 1.5-inch diameter pipes
7 feet for 2-inch diameter pipes
9 feet for 3-inch diameter pipes
11 feet for 4-inch diameter pipes
13 feet for 6-inch diameter pipes
15 feet for 8-inch diameter pipes
18 feet for 10-inch diameter pipes
22 feet for 12-inch diameter pipes

However, it is important to note that these are general guidelines and the actual span may vary depending on the specific application and the design criteria used. It is always recommended to consult with a qualified engineer or piping designer to determine the appropriate support span for a specific HDPE piping system.

F. GRE Pipe Support Span

The maximum allowable span for Glass Reinforced Epoxy (GRE) pipes will depend on various factors, such as the pipe diameter, wall thickness, and the type of fluid being transported.

The Fiberglass Reinforced Plastic Institute (FRPI) provides guidelines for designing supports for GRE pipes, which includes recommendations for maximum allowable span. According to FRPI, the maximum allowable span for GRE pipes should not exceed the following:

2 feet for 1-inch diameter pipes
2.5 feet for 1.25-inch diameter pipes
3 feet for 1.5-inch diameter pipes
4 feet for 2-inch diameter pipes
6 feet for 3-inch diameter pipes
7 feet for 4-inch diameter pipes
8 feet for 6-inch diameter pipes
10 feet for 8-inch diameter pipes
12 feet for 10-inch diameter pipes
14 feet for 12-inch diameter pipes

It is important to note that these are general guidelines and the actual span may vary depending on the specific application and the design criteria used. It is always recommended to consult with a qualified engineer or piping designer to determine the appropriate support span for a specific GRE piping system.

ISO 14692-2002 also provides a typical GRE pipe support span table to be used for FRP/GRE pipes in Table 1 (The same is reproduced below in Fig. 4).

**Fig. 4: GRE Pipe Support Span as per ISO 14692-2002**

G. ABS and PVC Pipe Support Spacing

PVC and ABS pipe support spacing is mainly based on the manufacturer. The following image (Fig. 5) provides some typical values for ABS and PVC Pipe Support Spans.

**Fig. 5: Horizontal Support Spacing for PVC and ABS Pipes**

H. Online Video Courses on Piping Support

To learn more about piping support design and engineering you can opt for the following video course.

Pipe Support Design and Engineering for Industrial Piping System

LPG Storage Tanks: Meaning, Types, Selection, Specification, and Design Calculations

Written by Anup Kumar Dey in Mechanical,Piping Design Basics,Piping Interface,Process

LPG (Liquefied Petroleum Gas) storage tanks or LPG Tanks are containers designed to store large quantities of propane or butane, which are commonly used as a source of fuel for heating and cooking in both residential and industrial applications. They are safe and efficient. LPG tanks are typically made of steel or another durable material that can withstand the high pressure and low temperatures required to store LPG in its liquid form. LPG is liquefied to maximize its storage efficiency inside the LPG Tanks.

LPG storage tanks come in various sizes, from small cylinders used for portable stoves and heaters to large tanks used for industrial purposes, such as powering forklifts and other heavy equipment. The capacity of LPG storage tanks can range from a few hundred liters to several thousand liters, depending on the specific application and the amount of LPG needed.

LPG tanks can be used in the form of LPG cylinders, LPG bulk tanks, Underground LPG storage tanks, etc. Flat-bottom cryogenic storage tanks are one variation of the most efficient LPG storage facility, having a capacity in the range of 1,000 to 30,000 m³.

LPG storage tanks must be designed and installed in compliance with strict safety regulations to prevent accidents and leaks. This includes regular inspection and maintenance to ensure that the tank is in good working condition and that any potential issues are addressed promptly.

Types of LPG Storage Tanks

There are several types of LPG storage tanks, each designed for specific applications and with varying capacities. Some of the most common types of LPG storage tanks include:

Aboveground LPG storage tanks: These are large tanks that are installed above the ground and are typically used for storing LPG in bulk for commercial and industrial applications.
Underground LPG storage tanks: These tanks are installed underground and are commonly used for storing LPG in residential areas where space is limited.
Horizontal LPG storage tanks: These tanks are designed to be installed horizontally and are commonly used for storing LPG in industrial settings.
Vertical LPG storage tanks: These tanks are designed to be installed vertically and are commonly used for storing LPG in residential areas and small commercial settings.
Mounded LPG storage tanks: These tanks are installed on a concrete platform or mound and are commonly used for storing LPG in industrial settings.
Propane cylinders: These are small portable tanks used for storing LPG for outdoor cooking and camping.
Cylindrical Storage Tanks
Spherical Storage Tanks

Each type of LPG storage tank has its own advantages and disadvantages, and the choice of the tank will depend on the specific application and the amount of LPG needed. Proper installation and maintenance are critical for ensuring the safe operation of LPG storage tanks.

Spherical or horizontal cylindrical type (bullet type) storage tanks are generally used to store LPG. The horizontal cylindrical types are usually used for small-capacity or underground installations and Spherical ones are used for higher capacities. The design of high-pressure LPG storage tanks is critical. Many parameters need to be considered during design. This article will provide basic information about the same.

Selection of LPG Storage Tank Types

A tank type will usually be selected considering the cost or the size of transportation. The spherical type is usually employed for sizes greater than 500 m³. The horizontal cylindrical type is usually used for sizes smaller than 100 m³. Both types will be applicable for volumes ranging from 100 to 500 m³. The type of this capacity range will be decided by the total weight. Where the tank is installed underground, the horizontal type shall be selected, even if the vessel capacity exceeds 100 m³.

LPG Storage Capacity

Definition of Capacity

Nominal capacity- All this capacity can be used, defined as below in Fig. 1. This capacity is usually used as a tank name.
Geometrical capacity- Volume inside a vessel which is called “a water volume” in NFPA.
Storage capacity- The volume from the tank bottom to the maximum design level. This volume varies depending on the operating temperature.
Net Working capacity- Volume between HLL and LLL or HHLL and LLLL

**Fig. 1: Figure explaining the storage tank capacity**

LPG Liquid Level

(1) Maximum liquid level (maximum Storage Capacity)

Many countries specify a maximum LPG liquid level (max. storage capacity) in their regulations. In countries that have no such regulations, NFPA shall be applied. NFPA-58 and 59 specify details of the maximum liquid level including liquid volume correction factors and equations concerning capacity and temperature (Refer to NFPA 58 Para. 4-4 and Appendix-F)

Few regulations specify that a vapor space of 10% shall be secured under the severest conditions, thus resulting in the following equation.

V = W/0.9d

Where V = tank geometrical volume (m³); W = Storage capacity (kg) and d = Density at the maximum design temperature (kg/m³)

NFPA specifies the coefficient of the above equation, i.e. 0.9 as follows.

9 to 0.95 at 100° F
98 to 0.99 at the maximum storage temperature.

This maximum liquid level fluctuates according to operating temperatures as below Example ;

The following figures are the results of example calculations according to the physical properties of Pure Propane per NFPA.

From the above, it is not possible to set a fixed level for the highest limit point. Therefore the highest limit of level should be compensated with the storage temperature or a differential pressure type level indicator shall be used.

(2) Minimum LPG levels

Refer to Fig. 2

H2; 150 mm or 10 minutes from the maximum filling volume

H3; A height of the Deadstock area. The height shall be calculated by the reasonable dead stock volume.

The recommended height for the spherical tank is shown below.

Where ;

D: Diameter of the sphere
H: Height of level
V: Sphere volume
Vb: Sectional Volume of the height H
H4: 300 mm/ minimum 100 mm

Note 1; High and low-level (HLL and LLL) alarms shall be set at the maximum and the minimum operation respectively. If high-high and low-low levels (HHL and LLL) for an emergency shutdown or an automatic diversion system are provided, set points shall be selected at lower than the maximum and higher than the minimum design, but not inside of the maximum and the minimum operation.

Sphere Maximum Capacity

The maximum sphere capacity is limited due to the wall thickness. The wall thickness is limited by the manufacturing and the stress relief requirement.

Operating and Design Conditions

Operating Conditions

(1) Operating temperature: Operating temperatures are not so important for the design of tanks; they are merely used to design pumps connected to tanks. The maximum operating temperature and minimum operating temperature as pump design bases shall be determined separately. The operating temperature of a tank shall be determined based on the following conditions.

The temperature of rundown from process units
Ambient air temperature (annual mean or annual highest mean temperature)
The temperature of products when they are received from a tanker.

(2) Operating Pressure: An operating pressure shall be an equilibrium pressure at operating temperature. Where the mole fraction of contents of the liquid in the tank fluctuates, the most severe case in normal operation shall be considered.

Design Conditions

(1) Design Temperature: A design temperature shall be determined based on the assumed highest temperature, with consideration given to input heat generated by solar radiation. Generally, design temperatures are specified per country based on the ambient air conditions of the district where the plant facilities are to be constructed. Major oil companies may have their own design standard for temperature selection. Where the country’s regulations or the client’s design standards do not specify design temperatures, NFPA shall be applied. Design temperature determination standards are closely connected with design pressures.

Major oil companies, in some cases, have specified the lowest design temperature as a design standard; they employ the equilibrium temperature of a tank internal at atmospheric pressure as the lowest design temperature. Low-temperature service materials, therefore, shall be used for tanks storing propane or lighter fluids.

(2) Design Pressure: The equilibrium pressure of a tank internal at the design temperature shall be used as the tank design pressure. Where the country’s regulations or the client’s design standards do not specify a design temperature, NFPA shall be applied as per the table below. Some major oil companies specify a higher temperature e.g. 65° C to be a mechanical design temperature, in their standards. In this case, however, they do not employ the equilibrium pressure of the internal at the specified temperature as design pressure, but the design pressure will be specified separately or the minimum design pressure specified in NFPA is otherwise used.

Note 1: Refer to NFPA 58, Para. 8-2.2

The NFPA specifies the equilibrium pressure at a design temperature of 41, 46, and 54° C, respectively, to be a design pressure, for each type of vessel as given below.

Vessels up to 4.5 m³ incl. in-capacity (54°C)
Vessels over 4.5 m³ in capacity (46°C)
Underground vessels (41°C)

LPG Storage Tank Nozzles

(1) Tank nozzle information to be provided by basic engineering. The following items of nozzle information shall be provided by the basic design group.

Size, number, and location of inlet and outlet nozzles. Note: The pump suction nozzle shall be inserted 300 mm from the tank bottom.
Size, number, and location of the sampling nozzle(s) and water draw-off nozzle, if required
Size and number of the spare nozzle(s), if required
Size and number of the vent and drain nozzle. A minimum of one vent and drain nozzle shall be provided.
Size and number of nozzles for safety relief valves. A minimum of one spare PSV shall be provided.

(2) Nozzle for instrumentation

Nozzle information for instrumentation will be provided by others.

(3) Nozzles to be decided by the detailed engineering group

The Instrumentation on LPG Storage Tanks

Level

Generally, two-level instruments will be installed to permit mutual calibration to be carried out, because LPG tanks cannot open without the tank shut down. One level instrument may be permitted if it is possible to remove and calibrate it by installing an isolation valve such as a radar type. To use the LPG tank capacity as effectively as possible, it is necessary to compensate the level with a temperature instrument or use a differential pressure type level instrument

Temperature

Generally, a temperature indicator shall be installed at the bottom crown

Pressure

Generally, two pressure gauges should be provided at the sphere’s top and bottom. One pressure instrument should be provided and indicated in the control room. Two pressure relief valves, each having a 100% capacity shall be provided. This configuration allows PRV maintenance without a sphere shutdown.

Water Drain

A Water draws offline shall be installed on each LPG tank. Two isolation valves shall be provided on the water draw offline: a distance of more than one meter shall be provided between the valves to prevent freezing the valves as figures below. As an alternative system, a water draw-off pot is provided, and the vent line from the water pot is returned to the flare line or the LPG tank.

Others

Insulation and Painting: For aboveground tanks, in some cases, cold insulation or fire protection may be provided, according to the client’s request. In such a case, it is possible to reduce the safety valve relieving capacity.

Tank Heaters or Coolers: A tank heater or cooler shall not be installed in the tank. However, an external heater may be required in the coldest areas, i.e. North East of China or Siberia, to avoid a vacuum in the tank.

Work Flow of LPG Storage Tank Basic Design

Codes and Standards for LPG Storage Tanks

There are several codes and standards that apply to the design, construction, installation, and operation of LPG storage tanks. These codes and standards are designed to ensure that the tanks are safe and reliable and that they comply with regulatory requirements.

Here are some of the key codes and standards that apply to LPG storage tanks:

NFPA 58: This is the National Fire Protection Association’s standard for the storage and handling of Liquefied Petroleum Gases (LPG). It provides requirements for the design, construction, installation, and maintenance of LPG storage tanks, as well as guidelines for emergency procedures and training.
ASME Boiler and Pressure Vessel Code: This code provides rules for the design, fabrication, and inspection of pressure vessels, including LPG storage tanks. It covers a wide range of factors, such as materials, pressure ratings, welds, and nondestructive examination.
API 2510: This is the American Petroleum Institute’s recommended practice for the design and construction of LPG storage facilities. It provides guidance on the selection of tank materials, tank size, and tank location, as well as requirements for tank foundations, piping systems, and safety equipment.
DOT Regulations: The US Department of Transportation (DOT) has regulations that govern the transportation of hazardous materials, including LPG. These regulations cover the design, construction, and testing of LPG cylinders, as well as requirements for labeling, marking, and documentation.
State and Local Regulations: In addition to federal regulations, there may be state and local regulations that apply to the installation and operation of LPG storage tanks. These regulations can vary widely depending on the location, so it is important to consult with local authorities and experts in the field.

By following these codes and standards, LPG storage tanks can be designed, installed, and operated safely and efficiently, with minimal risk to people and the environment.

Materials for LPG Storage Tanks

LPG storage tanks can be made from a variety of materials, depending on the specific requirements of the application. Some common materials used for LPG storage tanks include:

Steel: Steel is a common material for LPG storage tanks, due to its strength, durability, and resistance to corrosion. Steel tanks can be either aboveground or underground, and can be coated or painted to provide additional protection against corrosion.
Stainless steel: Stainless steel is a common material used for cryogenic LPG storage tanks. It has good strength, durability, and resistance to corrosion at low temperatures.
Nickel alloys: Nickel alloys, such as Inconel or Monel, can be used for cryogenic LPG storage tanks. They have good resistance to corrosion and embrittlement at low temperatures.
Aluminum: Aluminum is another material that can be used for LPG storage tanks. Aluminum tanks are lightweight and corrosion-resistant, making them a good option for portable applications or locations with high humidity or salt air.
Composite materials: Composite materials, such as fiberglass-reinforced plastic (FRP) or carbon fiber, can be used for LPG storage tanks. These materials are lightweight, corrosion-resistant, and have good impact resistance.
Concrete: Concrete tanks can be used for underground storage of LPG. Concrete tanks are durable and can withstand high pressure, making them suitable for large-scale industrial applications.

LPG Storage Tank Sizes

LPG storage tank sizes can vary widely, depending on the specific application and the amount of LPG that needs to be stored. Some common LPG storage tank sizes include:

Small LPG cylinders: These are typically used for portable applications, such as camping or outdoor cooking. They typically have a capacity of 1-20 pounds (0.5-9 kilograms) of LPG.
Residential LPG tanks: These are often used to supply propane for heating and cooking in homes. They typically range in size from 100 to 1,000 gallons (380 to 3,785 liters) of LPG.
Commercial LPG tanks: These tanks are used to supply propane for commercial applications, such as fueling forklifts or powering industrial equipment. They typically range in size from 1,000 to 30,000 gallons (3,785 to 113,562 liters) of LPG.
Industrial LPG tanks: These tanks are used to supply LPG for large-scale industrial applications, such as power generation or chemical manufacturing. They can range in size from 30,000 to 250,000 gallons (113,562 to 946,353 liters) of LPG or more.

The specific LPG storage tank size that is required will depend on several factors, including the amount of LPG needed, the location and environment in which the tank will be installed, and the specific regulations and safety standards that apply to the installation. It is important to work with an expert in LPG storage tank installation to determine the appropriate tank size for the specific application.

LPG Storage Tank Specification

To specify an LPG storage tank, several factors need to be considered, including the required storage capacity, the type of LPG being stored, the location and environment in which the tank will be installed, and the specific regulations and safety standards that apply to the installation.

Here are some key steps to consider when specifying an LPG storage tank:

Determine the required storage capacity: The storage capacity of the tank will depend on the amount of LPG required for the intended application. This may be based on factors such as the size of the property, the number of appliances being powered by the LPG, and the expected usage patterns.
Identify the type of LPG: There are different types of LPG, including propane and butane, and the tank must be designed to store the specific type of LPG being used.
Choose the appropriate tank type: Based on the required storage capacity and the intended application, select the appropriate type of LPG storage tank, such as aboveground, underground, horizontal, or vertical.
Consider location and environment: Determine the location and environment in which the tank will be installed, taking into account factors such as accessibility, ventilation, and weather conditions.
Check regulations and safety standards: Ensure that the installation complies with all relevant regulations and safety standards, including local building codes and fire safety regulations.
Consult with an expert: Consult with an expert in LPG storage tank installation to ensure that the tank is properly specified and installed and that all safety and regulatory requirements are met.

By following these steps, it is possible to specify an LPG storage tank that meets the specific needs of the application while ensuring safety and compliance with regulations.

Uses of LPG Tanks

Liquefied petroleum gas is used in a number of applications. So in all such applications, the LPG tanks are required to store the LPG. Some of the typical uses of LPG Tanks are:

Heating homes.
Cooking appliances.
Alternative fuel for cars and other vehicles.
Refrigerant.
Industrial uses like
- as an energy carrier.
- as feedstock for the chemical synthesis.
- for facilitating the different industries’ access to this substance.

What Is Modal Analysis and Why Is It Necessary? Caesar II Piping Modal Analysis Steps

Written by Anup Kumar Dey in Caesar II,Civil,Piping Stress Analysis

Modal analysis is a powerful technique used in vibration engineering fields to understand the dynamic behavior of structures, mechanical systems, piping and pipeline systems, and other physical entities. It plays a crucial role in optimizing designs, improving product performance, and ensuring the safety and reliability of various engineering applications. In this comprehensive guide, we will delve deep into the world of modal analysis, to learn the following:

Meaning of Modal Analysis
Why is Modal Analysis Important?
Criteria for Modal Analysis of Piping System
Applications of Modal Analysis
Modal Analysis Methods
Piping Modal Analysis Software Programs
Caesar II Piping Modal Analysis Procedure
And Many more…

What is Modal Analysis?

Modal analysis is a technique used to study the dynamic characteristics of structures and systems. It provides valuable insights into how these entities respond to external forces or vibrations. Modal Analysis is the study (analysis) of the dynamic behavior (dynamic analysis) of the structural, piping, or pipeline system and is used to find the natural frequencies of vibration for the concerned structural system. Different modes of vibration (vibration characteristics) of the analyzed piping system are determined using Modal Analysis. The modal analysis helps to show the movement of different parts of the structure under dynamic loading conditions.

The primary goal of modal analysis is to determine the natural frequencies, mode shapes, and damping ratios of a system, which collectively describe its dynamic behavior.

Natural Frequencies:

These are the frequencies at which a structure or system tends to vibrate when subjected to an external force or disturbance. Natural frequencies are characteristic of the system’s mass, stiffness, and geometry.

Mode Shapes:

Mode shapes represent the spatial distribution of motion within a structure or system at a specific natural frequency. They describe how different parts of the system move in relation to each other during vibration.

Damping Ratios:

Damping ratios quantify the energy dissipation in a system, indicating how quickly vibrations decay after an external disturbance is removed.

Why is Modal Analysis Important?

Modal Analysis provides an overview of the limits of the response of a system. All elements of the piping systems like flanges, valves, pipes, etc. have an internal frequency at which they vibrate naturally. At this frequency, the components will allow an energy transfer from one form to another with minimal loss. When this frequency reaches the “resonant frequency,” the system amplitude increases to infinity, and high vibration is observed. Hence, modal analysis is used to find out all such frequencies so that the occurrence of resonance can be prevented. Modal analysis is also known as modal and frequency analysis.

Natural frequencies give us an idea of how fast the piping system is going to vibrate. The term natural means, that the system is in free motion without any external forces. So by performing modal analysis the following two points are discovered

The natural frequency of the piping system and
The corresponding modes of vibration

Criteria for Modal Analysis of Piping System

While performing stress analysis for piping/pipeline systems you might have come across the term two-phase flow. Most of the flowlines are believed to have two-phase flow. Several processes and oil & gas piping systems, too, carry the two-phase flow. Conventionally all two-phase flow (Slug Flow) lines are believed to be vibration-prone.

The stress analysis basis or flexibility specification of most of the relevant organizations informs the stress engineers to perform modal analysis for such systems and properly support these lines using hold-downs, guides, and axial stops to reduce the extent of vibration. It is a standard engineering practice to keep the natural frequency of vibration-prone lines in excess of 4 Hz. Now the question is how to calculate the natural frequency or modal frequencies of a complex piping system.

The modal analysis module of Caesar II dynamic analysis is also used to calculate the natural frequency of pipe systems connected to compressors and reciprocating pumps. Harmful vibrations will result when the pipe’s natural frequency is close to that of connected rotary equipment. In order to avoid resonance and subsequently fatigue failure, many organizations follow the below-mentioned two criteria while modal analysis

f/f_n>1.25 and
f/f_n<0.75

Here, f=excitation frequency of the rotating equipment and f_n=piping natural frequency.

Applications of Modal Analysis

The modal analysis finds applications in various fields, including:

Structural Engineering: In civil engineering, modal analysis helps assess the dynamic response of buildings and bridges to earthquakes, wind loads, and other environmental factors. It aids in designing structures that can withstand these forces and prevent catastrophic failures.
Aerospace Engineering: Modal analysis is used to study the vibrations and dynamic characteristics of aircraft, spacecraft, and rocket components. This information is crucial for designing lightweight yet robust structures to enhance fuel efficiency and safety.
Mechanical and Piping Engineering: In mechanical and piping systems, modal analysis assists in optimizing the design of components like engine parts, automotive suspensions, industrial machinery, and piping systems. It ensures that these components operate efficiently and do not fail under dynamic loading conditions.
Automotive Industry: Modal analysis is used to evaluate vehicle chassis and suspension systems to improve ride comfort and handling. It also plays a role in reducing noise, vibration, and harshness (NVH) in automobiles.
Electronics and MEMS: Modal analysis is applied to micro-electro-mechanical systems (MEMS) and electronic components to understand their dynamic behavior and improve reliability.

Methods of Modal Analysis

Modal analysis can be performed using various methods, including:

Experimental Modal Analysis (EMA): This involves measuring the dynamic response of a physical system using sensors (e.g., accelerometers) and then extracting modal parameters through mathematical techniques like the Fast Fourier Transform (FFT) or system identification.
Operational Modal Analysis (OMA): OMA is conducted on an in-service structure or system without artificially inducing vibrations. It relies on ambient vibrations or external excitations (e.g., traffic loads) to extract modal parameters.
Numerical Modal Analysis: Numerical simulations, such as finite element analysis (FEA) or computational fluid dynamics (CFD), are used to predict the natural frequencies and mode shapes of a system based on its geometric and material properties. This method is often employed in the design phase.

Significance of Modal Analysis

The modal analysis offers several significant benefits:

Design Optimization: By understanding a system’s dynamic behavior, engineers can make informed design choices to improve performance, reduce vibrations, and enhance durability.
Failure Prediction: Modal analysis can identify potential failure modes and structural weaknesses, allowing for preemptive maintenance or design modifications.
Quality Assurance: Manufacturers can use modal analysis to ensure that products meet performance specifications and standards, leading to higher-quality and more reliable products.
Safety: In civil and aerospace engineering, modal analysis contributes to the safety and integrity of structures and vehicles by ensuring they can withstand dynamic loads and environmental conditions.
Cost Savings: By avoiding overdesign and optimizing structures or systems, modal analysis can lead to cost savings in terms of materials and manufacturing.

Software for Piping Modal Analysis

Various software is available in the market to determine modal responses of structures by modal analysis. For piping and pipeline systems modal analysis is performed using the following software

ANSYS
Caesar II
AutoPipe
Start-Prof
Rohr 2
Caepipe

Out of the above, Caesar II by Hexagon is the most widely used software for modal analysis of Piping Systems.

Dynamic Modal Analysis Module of Caesar II

So, here comes the importance of a Caesar II dynamic module called the Modal analysis module. The complex job of calculating the natural frequency of the piping system becomes very easy with the use of this module. The vibration response or dynamic response of any system can be easily determined using modal analysis. In the actual case, Modal analysis breaks up a complex system into a number of modes of vibration, each of which has a unique vibration response. This article will elaborate on the steps followed for performing the modal analysis using Caesar II.

Modal Analysis Steps in Caesar II

To start the modal analysis you must have a stress system. So from the isometric model, the system follows conventional methods and perform the static analysis and make the system safe in all respect with respect to static analysis. Now follow the below-mentioned steps for dynamic Modal analysis:

Caesar II Modal Analysis Procedure

Click on Analysis-Dynamic Analysis as shown in Fig. 1 to open the dynamic module in Caesar II. It will open the window which is shown in Fig. 2.

**Fig.2: Selection of Modal Analysis in Dynamic Module in Caesar II**

Now click on Analysis type and select Modal from the drop-down menu. You will get the following window as shown in Fig. 3.

You will get four input spreadsheets as lumped masses, snubbers, control parameters, and advanced.

Click on Control parameters and it will open the window shown in Fig. 4.

Change the frequency cut-off to your desired frequency based on your project specification. If you need to arrest all frequencies below 5 Hz and set that value as 5. The stiffness factor for friction can be used up to a value of 100. However, few organizations prefer not to use friction forces in dynamic analysis so use the stiffness factor as zero.

Now select the static load case for which you want to extract the natural frequencies. Normally it is advisable to select the operating temperature case.

**Fig.4: Input data for Dynamic Modal Analysis**

Run the Modal Analysis

Now you are set for analysis, So click on the run button similar to what you do for static analysis. The analysis will extract all the natural frequencies in which the piping system will experience below your cut-off frequency values. Fig. 5 shows such a typical modal run screen.

**Fig.5: A Typical Caesar run result of modal analysis**

How to interpret Modal Analysis Results

After the analysis run is complete the output screen will open. Select Natural frequencies to check the extracted natural frequencies of the system. Most of the time we check the animation view to get a feel of the actual vibration process. Select Natural frequencies and then click on the animation button as shown in Fig. 6.

**Fig.6: Selection of animation button during Modal Analysis**

In the animation, view and check how the system is experiencing vibration. Accordingly, provide support. Normally guide and line stop support with zero gaps will be required to arrest the vibration frequencies. Accordingly, provide support. Sometimes hold-down supports will be required. So, each time in the animation view find out the location where the system is vibrating and provide support near it. In most cases, the vibration occurs

Near rigid bodies (valves, flanges, etc.)
Long unsupported pipe spans
Long pipe runs where guide support is not provided
Straight lengths of pipe without line stops

So each time provide support at vibrating places in the piping system and re-run the modal analysis as mentioned above.

As soon as you provide a guide and line stop supports the system will become more rigid and expansion stresses will increase. So each time you change some support type you have to perform static analysis and make the system safe from all considerations and then proceed to the dynamic module.

Video tutorial on Modal Analysis Basics and related theories

The following video tutorial gives a nice explanation of the modal analysis basics and modal analysis theories.

Video Tutorial on Modal Analysis Basics and Modal Analysis Theories

Modal analysis is a vital tool in the field of engineering, enabling us to unlock the secrets of dynamic behavior in structures and systems. Whether it’s arresting the vibration of piping and pipeline systems, designing safer buildings, improving the performance of vehicles, or enhancing the reliability of electronic components, modal analysis plays a crucial role in shaping the modern world. With ongoing advancements in technology and analytical techniques, modal analysis continues to evolve, opening up new possibilities for innovation and engineering excellence.

Few more useful resources for you.

Slug Flow Analysis Using Dynamic Spectrum Method in Caesar II

Basics of Pipe Stress Analysis

Piping Layout and Design Basics

Pump Commissioning and Start-Up: Pump Commissioning Checklist

Written by Anup Kumar Dey in Mechanical,Piping Design Basics,Piping Interface

Pre-requisites for commissioning and start-up of a Process Pump:

Before commissioning and starting up of any equipment some preparation must be done. There will be some mandatory requirements, that should be fulfilled. So Process Pump is not an exception. At the same time process pumps, being vibration prone and sensitive, the utmost care has to be exercised. So before starting up the pump set, make sure that the following requirements are met:

The pump set has been properly connected to the electric power supply and is equipped with all protective devices.
The pump has been primed with the fluid to be handled.
The direction of rotation has been checked. (The correct direction of rotation of motor and pump is in the clockwise direction (seen from the motor end))
All auxiliary connections required are connected and operational.
The lubricants have been checked.

Filling in the lubricant in bearing bracket of Process Pump:

Fill the bearing bracket of the Process Pump with lubricating oil. The constant-level oiler is screwed into the upper tapping hole of the bearing bracket. If no constant-level oiler is provided on the bearing bracket, the oil level can be read in the middle of the oil level sight glass arranged at the side of the bearing bracket. Note that Insufficient lubricating oil in the reservoir of the constant-level oiler damages the bearings. So

Regularly check the oil level.
Always fill the oil reservoir completely.
Keep the oil reservoir properly filled at all times.

Bearing Bracket with constant level oiler of typical Process Pump

Remove the protective cage.
Unscrew the vent plug (2).
Hinge down the reservoir of the constant-level oiler (1) from the bearing bracket (5) and hold it in this position.
Pour in the oil through the vent plug tapping hole until oil appears in the connection elbow of the constant-level oiler (3).
Fill the reservoir of the constant-level oiler (1) with oil up to the maximum level.
Snap the reservoir of the constant-level oiler (1) back into the operating position.
Screw the vent plug (2) back in.
Fit the protective cage.
After approximately 5 minutes, check the oil level in the reservoir of the constant-level oiler (1). It is important to keep the reservoir properly filled at all times, to ensure an optimum oil supply. Repeat steps 1 – 8, if necessary.
To verify the correct function of the constant-level oiler (1), slowly drain the oil through the drain plug (4) until air bubbles can be seen in the oiler.

Note that, An excessively high oil level can lead to a temperature rise and to leakage of the fluid handled or oil.

Shaft seal

Shaft seals are fitted prior to delivery.
Observe the instructions on dismantling or reassembly on the operator’s manual.
If applicable, fill the reservoir of non-pressurized external fluid in accordance with the general arrangement drawing.
Prior to starting up the pump, apply barrier pressure as specified in the general arrangement drawing.
Apply the quantities and pressures specified in the datasheet and the general arrangement drawing.

Filling and venting the Process Pump:

Before starting up the pump set, vent the pump and suction line and fill both with the fluid to be handled.

Vent the pump and suction line and fill both with the fluid to be handled.
Fully open the shut-off element in the suction line.
Fully open all auxiliary connections (barrier fluid, flushing liquid, etc).

Final check before Starting the Process Pump:

Remove the coupling guard and step guard, if any.
Check the coupling alignment; re-align the coupling, if required.
Check that the coupling and shaft can easily be rotated by hand.
Re-install the coupling guard and step guard, if any.
Check the distance between coupling and coupling guard. The coupling guard must not touch the coupling.

Water cooling:

Observe the cooling water quality. Also, observe the following quality data of the cooling water:

Not deposit forming
Not aggressive
Free from suspended solids
Hardness on average 5 °dH (~1mmol/l)
pH > 8
Conditioned and neutral with regard to mechanical corrosion
Inlet temperature tE= 10 to 30 °C Outlet temperature tA= maximum 45 °C

Cooling of the pump:

The casing cover, the bearing bracket and the casing support on the baseplate can be cooled. Observe the following quality data of the cooling water:

Maximum permissible cooling liquid pressure: 10 bar
Maximum permissible cooling liquid test pressure: 15 bar
Observe the specified cooling liquid quantity.

Cooling of the shaft seal:

Cool the shaft seal.
Provide sufficient quantities of cooling liquid (see table).

Cooling Liquid Quantities for Process Pump Operation

Heating up/keeping warm the pump (set):

Prior to pump start-up, heat up the pump as described in the operating manual. Observe the following when heating up the pump (set) and keeping it warm:

Make sure the temperature is increased continuously.
Max. heating speed: 10 °C/min (10 K/min)

If the pump is used for handling fluids with fluid temperatures exceeding 150 °C, make sure that the pump has been heated throughout before starting it up. The temperature difference between the pump’s surface and the fluid handled must not exceed 100 °C (100 K) when the pump is started up.

Start-up:

Fully open the shut-off valve in the suction head/suction lift line.
Close or slightly open the shut-off valve in the discharge line.
Switch on the motor.
Immediately after the pump has reached full rotational speed, slowly open the shut-off valve in the discharge line and adjust it to comply with the duty point.
When the operating temperature has been reached and/or in the event of leakage, switch off the pump set and let it cool down. Then retighten the bolts between lantern and casing.
Check the coupling alignment and re-align the coupling if required.

Check that

The piping system connected to the pump set has been cleaned.
Pump, suction line and inlet tank, if any, have been vented and filled with the fluid to be pumped.
The filling and venting lines have been closed.
Never operate the pump with the shut-off elements in the suction line and/or discharge line closed.
Only start up the pump set with the discharge side gate valve slightly or fully open.
Never operate the pump set without liquid fill.
Prime the pump as specified. (⇨ Section 6.1.4 Page 31)
Always operate the pump within the permissible operating range.

In case of Abnormal noises, vibrations, temperatures or leakage

Switch off the pump (set) immediately.
Eliminate the causes before returning the pump set to service.

Checking the shaft seal

The mechanical seal only leaks slightly or invisibly (as vapor) during operation. Mechanical seals are maintenance-free.

Operating limits

Comply with the operating data indicated in the datasheet.
Avoid prolonged operation against a closed shut-off valve.
Never operate the pump at temperatures exceeding those specified in the datasheet or on the nameplate unless the written consent of the manufacturer has been obtained.

Ambient temperature

Observe the specified limits for permissible ambient temperatures.

Permissible ambient temperature: Maximum 43 °C: Minimum See datasheet

Frequency of starts

The frequency of starts is usually determined by the maximum temperature increase of the motor. This largely depends on the power reserves of the motor in steady-state operation and on the starting conditions (d.o.l., star-delta, moments of inertia, etc). If the start-ups are evenly spaced over the period indicated, the following limits can be used for orientation for a start-up with the discharge-side gate valve slightly open:

Do not re-start the pump set before the pump rotor has come to a standstill.

The density of the fluid handled

The power input of the pump increases in proportion to the density of the fluid handled. Hence always observe the information on fluid density indicated in the datasheet and make sure the power reserve of the motor is sufficient.

Abrasive fluids

Do not exceed the maximum permissible solids content specified in the datasheet. When the pump handles fluids containing abrasive substances, increased wear of the hydraulic system and the shaft seal are to be expected. In this case, reduce the intervals commonly recommended for servicing and maintenance.

Pump Commissioning Checklist

The commissioning of Process Pumping systems is a complex process that requires a structured approach. A pump commissioning checklist validates the operation of pumps through correct installation, proper lubrication, and simulation of instrumentation and protection devices. The following checklist highlights some of the areas that need to be verified when commissioning pumping systems:

Pumps in place and properly grouted, anchoring installed as per specification
- Pump tag and nameplate permanently affixed
- Pump environment clean with adequate access for maintenance
- Distribution piping complete, including pipe fittings and accessories, bleed and makeup water lines and safety reliefs; piping type and flow direction labeled on piping, valves properly tagged
- System flushing complete and strainers cleaned
- Required valves and balancing valves installed and balancing completed; TAB report reviewed for pump flows, pressure or head, electrical data
- Temperature, pressure, and flow gauges and sensors installed per specification; test ports installed near all control sensors
- Flow switch and flow meters installed as required and per specification
- Expansion tanks verified to not be air-bound and system completely full of water
- Air vents and bleeds at high points of systems functional
- Vibration isolation devices installed and functional
- Factory alignment/field alignment correct
- No visible leaks
- Pump lubricated
- Automatic valves stroke fully and close tightly
- Pump electrical supply disconnects in place and labeled; all electrical connections tight
- Motor safeties in place and operable
- All control devices, tubing, and wiring complete; control system interlocks hooked up and functional
- Water treatment system or plan installed
- VFD commissioned in accordance with the manufacturer’s instructions.
Specific commissioning actions will depend on the type and extent of the system to be commissioned.

References:

https://www.sampumps.com/commissioning.php

High Temperature and High-Pressure Piping

Written by Anup Kumar Dey in Piping Design Basics,Piping Stress Analysis,Piping Stress Basics

What is Pressure Piping?

Pressure piping is any piping that carries fluid under internal or external pressure. ASME B31 serves as the design code for pressure piping. All process piping, power piping, and pipelines all are examples of pressure piping.

What is High-Pressure Piping?

High-pressure piping is the piping that the owner designates as being a high-pressure fluid service. Appendix IX of ASME B 31.3 provides design rules for High Pressure Piping. These rules are slightly different from normal pressure piping. A high-pressure piping system as per ASME B31.3 is a system for which the design pressure is more than that allowed by the ASME B16.5 Class 2500 (PN 420) rating for the specified design temperature and material group. For stress analysis of piping systems suitable dynamic analysis and fatigue analysis is performed to avoid or minimize conditions that lead to detrimental vibration, pulsation, or resonance effects in the piping. However, in this article, we are not discussing these piping systems.

Effect of Pressure on Piping System

With an increase in fluid pressure in a piping system

Pipe thickness increases increasing the rigidity of the system
Flange rating increases which increases flange and valve thicknesses.
An increase in thickness increases the loads on pipe supports and tie-in points.
The overall cost of the piping system and design increases

Effects of Temperature on Piping System

Temperature change creates expansion or contraction in the piping system creating thermal stresses.
At high temperatures (T>T_melting/3), creep starts.
With an increase in temperature, allowable stress values (Sh) reduce, making the system more prone to failure.
With the change in temperature, the corrosion mechanism and corrosion rate change.
At lower temperatures, reduction of Charpy V-Notch values and K_IC (Fracture Mechanics) are observed requiring special considerations.

High Temperature and High-Pressure Piping

With an increase in temperature and pressure, piping systems become more and more critical from a stress point of view. So, Piping Stress Engineers have a really tough time qualifying all their systems as material allowable drops with an increase in temperature. This article will try to list the impacts that these two process parameters impart in piping stress systems.

Major Characteristics of High Temperature and High-Pressure Piping

With respect to high temperature and high-pressure conditions in piping, the following are the typical features-

The higher the pressure in the pipe, the higher is the thickness of the pipe. Higher thickness means more rigid and less flexible. All these cause a higher load on the supports, and higher frictional components acting axially and laterally, which in turn can cause higher loads on the equipment nozzles.

The higher the temperatures, the higher are the pipe movements – vertical, axial, and lateral. This also causes higher frictional forces in the system. At the same time, high-temperature piping has low allowable stresses as with an increase in temperature material allowable stress value reduces. So the qualification of stress systems becomes more difficult.

High Temperature and High Pressure Piping System — **Typical Example of High Temperature and High-Pressure Piping System**

Due to high movements, there are high strains and stresses in the piping system. This, in turn, leads to higher forces and moments on the supports and equipment nozzle.

Pipe supporting becomes complicated with the need to use special type supports like spring hangers, snubbers, anti-friction slide plates, etc. Also, with an increase in thermal movement long shoe supports come into the picture.

Depending upon the layout limitation use of expansion joints may become essential. Expansion joints are very expensive and difficult to maintain. Design Life of expansion joints is normally very less as compared to the piping systems.

The higher the temperature, the lesser is the allowable strength of the material. Consequently the more, the pipe and fittings will become prone to failure. The valves, gaskets, studs, etc. have to be of material to withstand that high temperature.

The choice of Studs/bolt materials becomes important at high temperatures.

For lines with high operating temperatures, hot bolting is done to take care of the expansion of the bolts at that high temperature.

Another thing that needs to be considered is the relaxation of bolts over a period of time. Special washers might be required to be used in such cases.

Welding external attachments/ appurtenances on very high-temperature pipes can cause thermal differential and induce cracking in the attachments.

High Temperature Piping System — **High-Temperature Piping System-Steam System**

During plant start-up, there is a possibility of two-phase flow in long pipes seeing high temperatures leading to thermal bowing.

At very high temperatures, the line may operate in a creep range leading to the permanent yielding of the materials. Thus such piping when cooled down during plant shutdowns does not come back to the original position of the piping. This is termed as the phenomenon of Thermal shakedown.

The material selected for high-temperature and high-pressure piping should be resistant to corrosion at higher temperatures.

As the temperatures increase in high-temperature piping systems, the insulation thickness is increased. Also at temperatures of the order of 650-700 degrees C, Ceramic wool is to be used instead of Rockwool which is used for normal 300-400 degree C piping. More insulation thickness means more weight loads in the system.

In places where the pipe displaces to a high degree over supports, cold pulls or offsets might be required.

Examples of High-Temperature Piping Systems

Some examples of the high-temperature piping system are listed below:

The Aromatics Platformer Reactor lines are at a temperature of about 520 degrees C
The Slop Wax / Vacuum Residue lines from the bottom of the Crude Column are at a temperature of 424 degrees C
The Vacuum Column – Heater Transfer line from the Vacuum Heater to the Vacuum Column is at a temperature of 396 degrees C
The FCCU Flue Gas line going to the Expander – Power Recovery Train at a temperature of 714 degrees C
In Coker, the coke cutting (hydro-jetting) lines see a pressure of 350 kg/cm2.
In Vacuum Gas Oil Unit the Reactor Circuit has lines with 360 degrees C and 97 kg/cm2
In CPP the Turbine lines at a temperature of 524 degrees C and Pressure of the order of 126 kg/cm².
The typical HP Steam (High-Pressure Steam) system has a temperature of up to 400 degrees C and a pressure of approximately 45 kg/cm2.
The typical MP Steam system has a temperature of up to 260 degrees C and a pressure of approximately 18 kg/cm2.
The typical LP (Low-Pressure) Steam system has a temperature of up to 200 degrees C and a pressure of approximately 5 kg/cm².

Based on the temperatures and the pressure in the piping, the material of construction needs to be selected.

Carbon Steel can be used up to 427 degrees C
Alloy Steel can be used up to 650 degrees C
Stainless Steel can be used up to 550 degrees C

Few more Resources for you..

Piping Design and Layout
Piping Materials
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Steel Pipeline Wall Thickness Calculation With Example

Written by Anup Kumar Dey in Pipeline,Piping Interface

Calculation of the minimum wall thickness of a given pipeline diameter and selection of actual thickness is one of the most important basic design considerations for any pipeline project. This is one of the basic activities that is performed at the initial stages of any detailed design project. In this article, the pipeline wall thickness calculation methodology will be explained for a liquid pipeline of 10-inch diameter (API 5L-Gr X52, 10.75-inch OD, Design Pressure=78 Bar-g, Design Temp=60 Deg. C) with a sample example.

Criteria for Minimum Pipeline Wall Thickness Calculation

The wall thickness for the CS Line pipe shall be calculated based on permissible hoop stress due to internal pressure. In accordance with ASME B31.4, clause 403.2.1, The nominal wall thickness of straight sections of steel pipe shall be equal to or greater than t_n determined by the following

Equation : t_n ≥ t + A

Here

A: sum of allowances for threading, grooving, corrosion, and erosion and an increase in wall thickness if used as a protective measure
t_n: nominal wall thickness satisfying requirements for pressure and allowances
t: pressure design wall thickness as calculated in inches (millimeters)

The line pipe wall thickness (t) to withstand the internal design pressure is calculated as below:

t = P * D / (2 * F S E)

Where

t : Calculated Wall thickness (mm)
P : Design pressure for the pipeline (kPa)=78 bar-g=7800 KPa
D : Outside diameter of pipe (mm)= 273.05 mm
F : Design factor = 0.72
S : Specified Minimum Yield Strength (MPa)=359870 KPa for the specified material.
E : Longitudinal joint factor = 1.0

Hence Calculated wall thickness (t, mm) = (7800*273.05)/ (2*0.72*359870*1) = 4.10

If the sum of allowances for threading, grooving, corrosion, and erosion and an increase in wall thickness is used as a protective measure=0.3 mm

Then nominal wall thickness satisfying requirements for pressure and allowances= 4.1+0.3= 4.4 mm.

So, any available thickness greater than 4.4 mm can be used as a selected thickness.

Now various organizations have their own guidelines for minimum thickness selection considering pipe rigidity, supporting, handling, field bending, and other aspects relating to construction and in-situ integrity of the pipeline and those need to be checked. Based on these, certain checks need to be performed before deciding the final wall thickness. These are listed below:

Some organizations limit the use of metallic line piping with a thickness of less than 4.8 mm. Hence 4.8 mm will be the selected thickness.

The diameter-to-wall thickness ratio should not exceed 96 for metallic pipelines for some organizations. Here D/T=273.05/4.8=56.88. In general, most codes inform to keep the D/T ratio less than 100 as additional checks will be required for to consider when D/T is equal to or more than 100.

Full Vacuum Collapse check

As per some organizations, collapse due to vacuum conditions shall be accounted for in the design of all pipelines, even when vacuum conditions are not expected to occur in service.

The calculations are carried out following pressure vessel code ASME Section VIII, DIV 1, UG-28. All vacuum collapse calculations are carried with nominal wall thickness excluding corrosion allowance.

As per UG 28 (f) of ASME section VIII, the selected pipeline wall thickness will be safe for full vacuum, if it is capable of withstanding a net external pressure of 1.01325 bar (15 psi).

Now following UG 28 equations (ASME BPVC Sec VIII) and graphs calculate allowable external working pressure. If the allowable external working pressure is more than the design external pressure (i.e., 1.01325 bar) then the selected thickness is satisfactory.

Equivalent Stress check

The equivalent stress calculations must be carried out as per ASME B31.4.

The wall thickness initially derived from hoop stress considerations based on design factors, should be such that the longitudinal, shear, and equivalent stresses in the pipe wall under functional and environmental loads do not exceed certain values. This is covered in ASME B31.4 Article 402 and ASME B31.8 Article 833. Because the requirements in these various articles differ from each other, it is recommended to use a single approach for all pipelines as detailed below.

The equivalent stress can be defined as follows:

S_eq = (S_h² + S_L²– S_hS_L+ 3S_s²)^1/2 (Von Mises equation)

S_eq = equivalent stress
S_h = hoop stress (due to pressure)
S_L = longitudinal stress (due to pressure, thermal expansion, and bending)
S_s = combined shear stress (due to torque and shear force)

The stress calculations for the operational phase shall be carried out with the nominal wall thickness excluding the corrosion allowance. The equivalent stress shall not exceed the values given below:

**Fig. 2: Allowable Equivalent Stress Limits**

Pipeline Wall Thinning Criteria Check

Changes in direction may be made by cold bending of pipe or installing factory-made bends or elbows. The bending of the pipe will result in a significant wall thinning. Hence, the wall thickness of finished bends, considering wall thinning at the outer radius, should be not less than the calculated wall thickness for Hoop Stress. The wall thinning calculations should be carried out following BS 8010.

As per BS 8010, An indication of wall thinning as a percentage can be calculated using the following equation:

Bend Wall Thinning =50/(n+1), %

This formula does not take into account other factors that depend on the bending process, and the bend manufacturer should be consulted where wall thinning is critical.

Here,

n=inner bend radius (Ri) divided by pipe outside diameter(D) for wall thinning formulae
R_i=Inner bend radius=(Bend Radius)-(OD/2)
The value of bend thinning shall be less than 2.5%.

Pipeline Strain Check

The strain induced in a pipeline by bending it along a radius R is =(Pipe OD)/2R (Bend Radius) the permanent bending strain should be within 2%.

Online Course on Pipeline Thickness Calculation

If you want to learn more and wish to check a case study, then I can suggest the following online video course which provides an example of pipeline thickness calculation for both restrained and unrestrained pipelines.

Pipeline Thickness Calculation Methodology with Example

Steel Pipeline Wall Thickness for Gas Pipelines

The pipeline wall thickness for gaseous products is calculated based on ASME B31.8, clause 841.1.1. The formula (When D/t>=30) is mentioned below:

t=(PD)/(2SFET) as per US unit or
t=(PD)/(2000SFET) in SI units.