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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>Tmelting/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 KIC (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
Piping Stress Analysis
Piping Stress Analysis using Caesar II
Piping Stress Analysis using START-PROF

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 tn determined by the following

Equation              :                    tn ≥ 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
  • tn:               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.

Pipeline Wall Thickness
Fig. 1: Pipeline Wall 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:

Seq = (Sh2 + SL 2– ShSL+ 3Ss2)1/2 (Von Mises equation)

  • Seq = equivalent stress
  • Sh = hoop stress (due to pressure)
  • SL = longitudinal stress (due to pressure, thermal expansion, and bending)
  • Ss = 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:

Allowable Equivalent Stress Limits
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
  • Ri=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.

Here,

  • t = nominal wall thickness, in. (mm)
  • D=nominal outside diameter of pipe, in. (mm)
  • E=longitudinal weld joint quality factor obtained from Table 841.1.7-1
  • F=design factor obtained from Table 841. 1.6- 1
  • P=design pressure, psig (kPa)
  • S=specified minimum yield strength, psi (MPa),
  • T=temperature derating factor obtained from Table 841.1.8-1

Differences between Pipeline Thickness Calculation as per ASME B31.4 and ASME B31.8

The methodology applied in pipeline wall thickness calculation for liquid pipelines and gas pipelines is almost similar. Only there are two major considerations:

  1. Consideration of Temperature Derating Factor: As liquid pipelines operate below 120 Degrees C as per ASME B31.4, the effect of temperature is not considered in the pipeline thickness calculation equation as per ASME B31.4. However, as gases can operate at higher temperatures (up to 232 Degrees C), the temperature effect is considered by using a factor known as the temperature derating factor. The value of the temperature derating factor up to a temperature of 120 degrees C is equal to 1.0 means both equations become the same below 120 degrees C temperature.
  2. Consideration of Design Factor: In general, the design factor for ASME B31.4 is 0.72 which is constant. However, in ASME B31.8 the design factor varies with respect to location class decided based on density of population and inhabitance.

The major differences between the pipeline wall thickness calculation as per liquid transportation pipeline code (ASME B31.4) and Gas Transportation Pipeline Code (ASME B31.8) are tabulated below:

AspectASME B31.4 (Liquid Pipelines)ASME B31.8 (Gas Pipelines)
ScopeLiquid hydrocarbons, anhydrous ammonia, other liquidsNatural gas, hydrogen gas, and other gases
Design Factor (F)Standard 0.72, reduced in populated areas0.72 (Class 1), 0.60 (Class 2), 0.50 (Class 3), 0.40 (Class 4)
Wall Thickness Formulat=PD/2SFEt=PD/2SFET
Temperature Derating FactorNot Applicable as the temperature limitation is up to 120 Deg CApplicable when the gas temperature is more than 120 degrees C. Up to 120 degrees C the value of Temperature derating factor T is equal to 1.
Location ClassesSimplified, with design factor reductions in sensitive areasDetailed location class system with varying design factors
Safety ConsiderationsLower safety margins due to the nature of liquid transportHigher safety margins due to the explosive nature of gases
Material StressFocus on material suitability for liquid transportEmphasis on preventing brittle failure, considering gas-specific factors
Testing & InspectionHydrostatic testing at 1.25 times design pressureHydrostatic testing at 1.5 times design pressure, more stringent inspections
Table 1: Differences in Pipeline Thickness Calculation Between ASME B31.4 and ASME B31.8

Bracing Connections/Cross-bracing Design Example

Written by Anup Kumar Dey in Civil,Piping Interface

Bracing Connections involve the bolting of flat, angle, channel, I-section, and hollow section members to a gusset plate to support the column or other members. The bracing member in a bracing connection can work in tension alone, or in both tension and compression and stabilize the main components by distributing the loads. In this article, we will explore the basics of bracing connections

Bracing connections serve as the backbone of many structural systems, providing lateral stability and helping resist forces like wind, seismic activity, and even the structural loads themselves. These connections transfer loads from the building or structure to the foundation, ensuring that it remains upright and safe even during extreme conditions.

Benefits of Structural Steel

Some benefits associated with the use of structural steel for owners are:

  • Steel allows for reduced frame construction time and the ability to construct in all seasons
  • Steel makes large spans and bay sizes possible, providing more flexibility for owners
  • Steel is easier to modify and reinforce if architectural changes are made to a facility over its life
  • Steel is lightweight and can reduce foundation costs
  • Steel is durable, long-lasting, and recyclable

Unique Aspects of Steel Construction

Procurement and management of structural steel are similar to other materials, but there are some unique aspects to steel construction:

  • Steel is fabricated off-site
  • On-site erection is a rapid process
  • This gives users of structural steel some scheduling advantages
  • Coordination of all parties is essential for achieving potential advantages

Forces on Structures

The structure will be subjected to various kinds of loads (Fig. 1) like

  • Forces from gravity, wind, and seismic events are imposed on all structures
  • Forces that act vertically are gravity loads
  • Forces that act horizontally, such as stability, wind, and seismic events (the focus of this discussion) require lateral load-resisting systems to be built into structures
  • As lateral loads are applied to a structure, horizontal diaphragms (floors and roofs) transfer the load to the lateral load-resisting system.
Forces acting on structures
Fig.1: Forces acting on structures

The type of lateral load-resisting system to be used in a structure should be considered early in the planning stage. Lateral stability and architectural needs must be met

The three common lateral load-resisting systems are:

  • Braced Frames (Fig. 2)
  • Rigid Frames (Fig. 2)
  • Shear Walls
Braced and Rigid Frames
Fig. 2: Braced and Rigid Frames

Steel Frame Connection Types

  • Simple Connections.
  • Moment Connections: Fully Restrained and Partially Restrained.
  • All connections have a certain amount of rigidity.
  • Simple connections (A above) have some rigidity but are assumed to be free to rotate.
  • Partially-Restrained moment connections (B and C above) are designed to be semi-rigid.
  • Fully-Restrained moment connections (D and E above) are designed to be fully rigid.
Steel frame connection types
Fig. 3: Steel frame connection types

Simple Connections

  • Designed as flexible connections.
  • Connections are assumed to be free to rotate.
  • Vertical shear forces are the primary forces transferred by the connection.
  • Require a separate bracing system for lateral stability.
  • The following few slides show some common simple framing connections.

Moment Connections

  • Designed as rigid connections that allow little or no rotation, Used in rigid frames.
  • Moment and vertical shear forces are transferred through the connection.
  • Two types of moment connections are permitted: Fully-Restrained and Partially-Restrained (Fig. 4).
Moment Connections
Fig. 4: Moment Connections

Rigid Frames

  • Rigid frames, utilizing moment connections, are well suited for specific types of buildings where diagonal bracing is not feasible or does not fit the architectural design
  • Rigid frames generally cost more than braced frames

Braced Frames

  • Diagonal bracing creates stable triangular configurations within the steel building frame
  • “Braced frames are often the most economical method of resisting wind loads in multi-story buildings.”
  • Some structures, like the one pictured above, are designed with a combination of braced and rigid frames to take advantage of the benefits of both

Temporary Bracing

  • Structural steel frames require temporary bracing during construction
  • Temporary bracing is placed before plumbing up the structural frame
  • This gives the structure temporary lateral stability
  • Temporary bracing is removed by the erector
  • In a braced frame, temporary bracing is removed after the final bolt-up is complete and the permanent bracing system is in place
  • In a rigid frame, temporary bracing is removed after the final bolt-up is complete

Concentric Braced Frames

Bracing is concentric when the center lines of the bracing members intersect Common concentric braced frames used in buildings today include:

  • Cross brace
  • Two-story X’s
  • Chevron
  • Single diagonals

Cross-bracing design is possibly the most common type of braces. Bracing can allow a building to have access through the brace line depending on the configuration

Cross-Bracing Design Example

  • The diagonal members of Cross bracing go into tension and compression similar to a truss.
  • The multi-floor building frame elevation shown above has just one braced bay, but it may be necessary to brace many bays along a column line
  • With this in mind, it is important to determine the locations of the braced bays in a structure early in a project
  • Connections for X bracing are located at the beam-to-column joints
  • Bracing connections may require relatively large gusset plates at the beam-to-column joint
  • The restriction of space in these areas may have an impact on the mechanical and plumbing systems as well as some architectural features
Different types of Bracing
Fig. 5: Different types of Bracing

Chevron Bracing

  • The members used in Chevron bracing are designed for both tension and compression forces
  • Chevron bracing allows for doorways or corridors through the bracing lines in a structure
  • Chevron bracing members use two types of connections
  • The floor-level connection may use a gusset plate much like the connection on X-braced frames
  • The bracing members are connected to the beam/girder at the top and converge to a common point
  • If gusset plates are used, it is important to consider their size when laying out mechanical and plumbing systems that pass through braced bays

Eccentrically Braced Frames

  • Eccentric bracing is commonly used in seismic regions and allows for doorways and corridors in the braced bays
  • The difference between Chevron bracing and eccentric bracing is the space between the bracing members at the top gusset connection
  • In an eccentrically braced frame bracing members connect to separate points on the beam/girder
  • The beam/girder segment or “link” between the bracing members absorbs energy from seismic activity through plastic deformation
  • Eccentrically braced frames look similar to frames with Chevron bracing
  • A similar V-shaped bracing configuration is used

Combination Frames

Figure showing Combination Frames
Fig. 6: Figure showing Combination Frames
  • As shown in Fig. 6 (left) a braced frame deflects like a cantilever beam while a moment-resisting frame deflects more or less consistently from top to bottom
  • By combining the two systems, reduced deflections can be realized
  • The combination frame is shown above right

Few more useful resources for you..

Structural Platforms: An In-Depth Guide
A Short Presentation on Pile Foundation and its Design
An article on Tank Pad Foundation
An Introduction to Braced Connections
A short article on “Sun Shade for oil and gas industry and their Design”
Considerations for Project Site Selection

Pump-Piping Alignment Check Methodology using Caesar II

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

Meaning of Pump Alignment Checking

“Alignment Checking” this term is quite familiar to piping engineers and all construction engineers. During piping installation at the construction site, it is expected that the equipment flange should match perfectly (aligned) with the piping flange so that during bolting no problem occurs.

But achieving that perfect alignment is very difficult. If this alignment for rotary equipment is not proper then there may be several problems in the future during operation which may lead to vibration of equipment/piping system or in some situations equipment failure.

Code Guidelines Regarding Rotary Equipment Alignment

American Petroleum Institute code API RP 686 provides the data for acceptable deviation from the ideal perfect alignment. As per the code if the vertical and horizontal deviation of the piping flange and rotary equipment flange centerline is within 1.5 mm and parallelism (rotation) is within 0.0573 degrees then the alignment is accepted otherwise means to be devised to bring the deviation within those values.

While performing stress analysis of rotary equipment connected piping systems in Caesar II we can very easily ensure this limitation. The following write-up will describe the step-by-step method of doing the same.

Alignment

 Alignment check of nozzle flange shall be performed for all Rotating Equipment like Centrifugal Compressor, Steam Turbine, Centrifugal Pumps, Gear Pumps, etc as per the following procedure.  

Alignment checking using Caesar II

Ensure the correct weight of the pipe (with proper thickness), Support weight (dummy pipe), Weight of valves, flanges, and any in-line items.

Consider Insulation density carefully (equivalent insulation density to be correctly fed with insulation & cladding weight, Check insulation on dummies for cold insulated lines).

Model all branch piping (like drip legs etc.) greater than 2 inches.

Discuss with a piping lead engineer the requirement of any maintenance flanges (Normally for steam turbine or centrifugal connected lines the maintenance flange is recommended) and include it if required.

Minimize the sustained load on the equipment nozzle as much as possible during the static analysis run of the Caesar model.

Normal industry practice is to analyze the Alignment checking in a separate file. So rename the static file as Filename_Alignment.C2

Make the equipment nozzle anchor flexible or remove the displacement if the anchor was not modeled. You can delete the equipment also if required.

Wherever spring support is used, define spring rate and cold load in case of variable effort spring & Constant effort support load in case of constant effort spring.

After performing the above create one additional load case in Caesar II as mentioned below:

WNC+H SUS System with spring hanger
WNC SUS System without spring hanger

Set the spring hanger as “As designed”.(Two load cases can be generated for spring As designed and rigid condition)

WNC Checking in Caesar II for Rotary Equipment
Fig. 1: WNC Checking in Caesar II for Rotary Equipment

Now run the analysis and check the displacements of the nozzle at the above-mentioned load case (WNC or WNC+H, as applicable) and limit them within below mentioned values:

Vertical deflection (Normally DY): +/- 1.5 mm
Horizontal displacement (sqrt sum of DX and DZ): +/- 1.5 mm
Parallelism (sqrt sum of RX and RZ): 0.0573 degrees.

In case, the above limitations are not met then re-analyze by readjusting the spring and other supports and do the simulation.

Few Notes for Pump Alignment Checking

  • An alignment check is to be performed for both inlet and outlet lines.
  • An alignment check must be performed with the spring under both “As designed” and in “locked” condition.
  • To avoid small misalignment in the vertical direction first support from the rotary equipment nozzle is used either spring support or adjustable type support.
  • For top nozzles, the advantage of the equipment can be taken (with approval from the client) as the equipment flange will support the piping flange during alignment.

Few more Useful Resources for you..

Shaft Alignment Methodology for Compressor and Driver
Connection procedure (Alignment) of Process Piping with Rotating Equipments: An Article
Alignment Check Methodology in Piping Stress Analysis using Caesar II
Few articles related to Pumps
Piping Design and Layout Basics

Pump Installation Checklist and Best Practices

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

Pump installation with proper methodology is an important activity. Improper pump installation could lead to vibration issues during pump operation. In this article, we will explore the pump installation best practices and pump installation checklists to reduce vibration problems.

What is Pump Installation?

Pump installation can be defined as the procedures or steps required to employ in the placement, alteration, and preparation for the operation of the pump without difficulty. Pump installation refers to the process of setting up and placing a pump system in its intended location, ensuring it is properly connected to the necessary components, and making it ready for operation. The goal of pump installation is to ensure that the pump operates efficiently, safely, and reliably in its intended application. Proper installation is essential to prevent issues such as leaks, vibrations, misalignment, and premature wear, which can lead to pump failure and reduced performance.

Steps for Pump Installation

Installing a pump correctly is essential for its efficient and safe operation. The actual pump installation steps may vary slightly depending on the types and models of pumps. However, in general, the following steps can be followed:

  • Step 1: Read the instruction manual thoroughly to understand any specific requirements and guidelines.
  • Step 2: Use a rigid, strong, and stable pump foundation. It should be level, secure, and clean of debris.
  • Step 3: Install the pump base on the foundation.
  • Step 4: In the next step, install the pump and the driver on the baseplate.
  • Step 5: Add oil to the proper level in the bearing housings
  • Step 6: Check initial pump alignment.
  • Step 7: Connect the suction and discharge piping.
  • Step 8: Complete a second alignment check, and readjust piping as needed. For long-term operation, proper alignment is critical.
  • Step 9: Perform a rotational check of the driver by disengaging the coupling element.
  • Step 10: Verify that the pump settings are correct.
  • Step 11: Install all ancillary equipment; coupling, and/or insert.
  • Step 12: Perform a pre-startup check, valves, electrical connections, etc., and prime the pump
  • Step 13: Recheck the pump alignment to ensure that fluid weight in the piping is not causing a misalignment.
  • Step 14: Start the pumping unit and verify that the pump is delivering the desired flow rate and pressure by checking pressures, flows, temperature, and other indicators.
  • Step 15: If there is any problem, make the necessary adjustments and rerun the pump.

Checklist for Pump Installation

Normally, organizations prepare a pump installation checklist to ensure that all relevant points are taken care of to ascertain the proper working of the pump. Most of such points are normally mentioned in detail in the pump operating manual provided by the pump manufacturer. Those points in the shorter form are listed in the pump installation checklists so that nothing is missed during actual installation time.

A pump installation checklist and best practices will ensure that major checkpoints are taken care of without missing any important considerations. The pump installation checklist is a document that lists in order of preference the considerations one must follow during the installation process. The checklist is usually grouped into various parts like:

  • Pump Pre-installation checklist
  • Pump Installation checklist
  • Pump Start-up checklist, etc

For the proper functioning of the centrifugal pumps in any plant, the following points need to be taken care of while installing.

Checking the site before the pump installation

The engineer should perform the following checks before the pump installation:

  • Make sure the foundation concrete is of sufficient strength.
  • Only place the pump set on a foundation whose concrete has been set firmly.
  • Only place the pump set on a horizontal and level surface.
  • Refer to the weights given in the Pump general arrangement (GA) drawing.
  • All structural work required must have been prepared in accordance with the dimensions stated in the outline drawing/general arrangement drawing.

Improper pump installation in potentially explosive atmospheres

Pumps required to operate in explosive atmospheres should ensure the following pump installation checks

  • Comply with the applicable local explosion protection regulations.
  • Observe the information in the datasheet and on the nameplates of the pump and motor.

Installing the pump assembly

Always install the pump set in a horizontal position to ensure proper self-venting of the pump. Refer to Fig. 1:

Figure showing the foundation of pump
Fig. 1: Figure showing the foundation of the pump

Position the pump on the foundation and use a spirit level to align the shaft and discharge nozzle. Permissible deviation: 0.2 mm/m. If required, use shims (2) to adjust the height. Fit shims between the baseplate/foundation frame and the foundation itself; always insert them to the left and right of the foundation bolts and in close proximity to these bolts.

For a bolt-to-bolt clearance > 800 mm, insert additional shims halfway between the adjoining holes. All shims must lie perfectly flush.

Insert the foundation bolts (4) into the holes provided. Use concrete to set the foundation bolts (4) into the foundation. Wait until the concrete has been set firmly and then align the baseplate. Tighten the foundation bolts (4) evenly and firmly.

Grout the baseplate using low-shrinkage concrete with standard particle size and a water/concrete ratio of ≤ 0.5.

Produce flowability with the help of a solvent.

For low-noise operation, the pump set can be mounted on vibration dampers upon confirmation by the manufacturer. In this case, only fasten the flexible elements at the baseplate after the piping has been connected.

Expansion joints can be fitted between the pump and the suction/discharge line.

Observe the permissible forces and moments at the pump nozzles and Take appropriate measures to compensate for the thermal expansion of the piping.

Check and ensure that the suction lift line/suction headline has been laid with a rising/downward slope towards the pump.

The nominal diameters of the pipelines are at least equal to the nominal diameters of the pump nozzles.

To prevent excessive pressure losses, adapters to larger diameters have a diffuser angle of approximately 8°.

Thoroughly clean, flush, and blow through all vessels, pipelines, and connections (especially of new installations). Before installing the pump in the piping, remove the flange covers on the suction and discharge nozzles of the pump.

Use a filter with laid-in wire mesh (mesh width 0.5 mm, wire diameter 0.25 mm) of corrosion-resistant material. Use a filter three times the diameter of the piping. Conical filters have proved suitable.

The volute casing and casing/discharge cover take on the same temperature as the fluid handled.

Make sure the space between the casing cover/discharge cover and the bearing cover is sufficiently vented. Never close or cover the perforation of the bearing bracket guards. Never insulate the casing cover and the bearing bracket.

Make sure that the coupling is correctly aligned at all times. Always check the coupling after the pump has been installed and connected to the piping. Also, check the coupling of pump sets supplied with the pump and motor mounted on the same baseplate. Refer to Fig. 2.

Checking the spacer-type coupling with a dial gauge
Fig. 2: Checking the spacer-type coupling with a dial gauge

Mark the installation position of the coupling by dotting marks (balancing condition).

Remove the coupling spacer. While the pump’s coupling is disengaged, also check the direction of rotation.

Check the alignment of the coupling halves with a dial gauge (see Fig. 2). Admissible run-out of coupling face (axial) maximum 0.1 mm. Admissible radial deviation, measured over the complete circumference, maximum 0.2 mm.

After having installed the pump set and connected the piping, check the coupling alignment and, if required, re-align the pump set (with the motor). Any differences in shaft center height between the pump and the motor are compensated by means of shims.

Check the coupling alignment.

Unscrew the hexagon head bolts at the motor. Insert shims underneath the motor feet until the difference in shaft center height has been compensated. Refer to Fig. 3.

Pump Set with Shim
Fig. 3: Pump Set with Shim

Re-tighten the hexagon head bolts. Check that the coupling and shaft can easily be rotated by hand.

Always operate the pump set with a coupling guard. If the customer specifically requests not to include a coupling guard in the Vendor’s delivery, then the operator must supply one! Observe all relevant regulations for selecting a coupling guard.

Reinstall the coupling guard and step guard, if any. Check the distance between the coupling and the coupling guard. The coupling guard must not touch the coupling.

Check the available mains voltage against the data on the motor nameplate.

Select an appropriate start-up method. Change the motor’s direction of rotation to match that of the pump.

Observe the manufacturer’s product literature supplied with the motor. Never check the direction of rotation by starting up the unfilled pump set. Separate the pump from the motor to check the direction of rotation.

Never insert your hands or any other objects into the pump. Check that the inside of the pump is free from any foreign objects.

The correct direction of rotation of the motor and pump is in the clockwise direction (seen from the motor end). If the direction of rotation is incorrect, check the connection of the motor and the switchgear, if any.

Overall, the pump installation should consider safety as the topmost priority.

Few more Useful Resources for you.

Vibration Related
Pump Related
Piping Design and Layout Basics
Heat Exchanger Related
Vessel Related

Stress Analysis of GRP / GRE / FRP Piping using START-PROF

Written by Alex Matveev in Piping Stress Analysis,Piping Stress Basics,Start-Prof

GRP / GRE / FRP / HDPE piping modeling in START-PROF is as easy as for steel piping. Your job is only to select the appropriate code and choose the material. That’s all!

Difference between GRE/GRP/FRP and Steel

The main differences between GRP / GRE / FRP piping to steel piping are:

The material is orthotropic. The stress values in axial as well as hoop direction need to be considered during analysis. Mechanical properties needed for analysis differ from steel piping: Ea – Elasticity modulus in the axial direction, Eh – Elasticity modulus in the hoop direction, G – Shear modulus, vh/a – Poisson ratio hoop/axial, va/h – Poisson ratio axial/hoop. Material properties are different for each vendor, so please ask the manufacturer for the values needed for stress analysis in the database.

Linear expansion for GRP / GRE / FRP piping is much greater than for steel piping. Pressure elongation is significant (Bourdon effect), and thermal expansion is also great. Due to uneven heating of pipe wall thickness, the real thermal expansion is lower than thermal expansion for the full temperature range. To consider this piping behavior thermal expansion is multiplied by the temperature range factor which is usually considered 0.85.

A long-term failure envelope is used instead of single allowable stress. See the material database for more details. Allowable stresses depend on load type factor f2, temperature factor A1, chemical resistance factor A2, and fatigue factor A3. A different envelope is used for pipes and fittings.

Modeling of GRP / GRE / FRP / Reinforced HDPE Piping using PASS/Start-Prof

To model GRP / GRE / FRP piping choose ISO 14692 code. This code is also suitable for modeling reinforced HDPE or other plastic piping:

Selecting piping code for Analysis
Selecting the piping code for Analysis

Then select material from the database:

Selecting the Material Database
Selecting the Material Database

That’s all. All other job is the same as steel piping.

The material Database contains all material properties. If there’s no material you need in the database, please ask your vendor to fill the table and add it to the database manually. Future pipe industries and NOV already provided needed data and it is included in the START-PROF database.

Selecting the Material Database
Sample Failure Envelope for GRE/GRP/FRP

All load cases for the ISO 14692 code will be created automatically. Just draw piping. After analysis, you get results according to ISO 14692 code.

Output Results after Analysis
Output Results after Analysis

Also, we did a job for the vendor of MRPP pipes to add material properties into the START-PROF database for 50-year service life, and now START-PROF is used for stress analysis of MRPP piping.

MRPP – an HDPE pipe, reinforced by a rigid steel carcass made of a welded wire.

MRPP
MRPP Pipes
MRPP Pipes

Stress Analysis Methodology

The complete video explaining the stress analysis methodology using Start/Prof is given below for your quick reference.

Download the FRP piping example file. See how to open the piping model file.

Online Video Course of FRP/GRP/GRE Pipeline Stress Analysis using Caesar II

If you are interested in learning FRP/GRE/GRP Piping Stress Analysis using Caesar II software, you can have a look at the following online video course