Widely Used Piping Codes and Standards

Written by Anup Kumar Dey in Piping Design Basics

The huge expansion of the piping industry where it is today is mainly for the available codes, standards, and recommended practices. The main concern for designing any process plant is the safety of the personnel involved. Design of Piping systems complying with these codes, standards, or recommended practices ensures safety along with standardization of required items. Every piping engineer should possess a basic knowledge of the extensively used piping codes and standards. The following write-up will try to provide a sum-up of common piping codes and standards that are extensively used in the process piping industry.

Difference between Piping Codes and Standards

Codes in the piping industry prescribe requirements for the design, materials, fabrication, erection, examination, assembly, test, and inspection of piping systems, whereas standards contain design and construction rules and requirements for individual piping components such as elbows, tees, returns, flanges, valves, and other in-line items.

Compliance with the code is generally mandated by regulations imposed by regulatory and enforcement agencies. At times, the insurance carrier for the facility leaves hardly any choice for the owner but to comply with the requirements of a code or codes to ensure the safety of the workers and the general public.

On the other hand, compliance with piping standards is normally required by the rules of the applicable code or the purchaser’s specification.

Recommended Practice

Recommended Practices, prepared by professional organizations or professional bodies are an optional set of documents that can be used for good engineering practice.

Even though every country has its own codes and standards but still the American codes and standards are most widely used. The major codes and standards which are used in the day-to-day piping applications are listed below:

A. ASME Codes for Piping Industry

ASME B31: Code for Pressure Piping

ASME B31.3 – Process Piping Code

This piping code normally provides rules for piping found in petroleum refineries, chemical, pharmaceutical, textile, paper, semiconductor, and cryogenic plants, and related processing plants and terminals including piping for fluids like raw, intermediate, and finished chemicals, petroleum products, gas, steam, air and water, fluidized solids, refrigerants, cryogenic fluids, etc. For process piping professionals this code is of utmost importance.

This Code does not provide information on the following:

(a) piping systems designed for internal gage pressures at or above zero but less than 105 kPa (15 psi), provided the fluid handled is nonflammable, nontoxic, and not damaging to human tissues and its design temperature is from −29°C (−20°F) through 186°C (366°F).
(b) power boilers and boiler external piping which is required to conform to ASME B31.1.
(c) tubes, tube headers, crossovers, and manifolds of fired heaters, which are internal to the heater enclosure
(d) pressure vessels, heat exchangers, pumps, compressors, and other fluid handling or processing equipment, including internal piping and connections for external piping.
(e) piping covered by ASME B31.4, B31.8, or B31.11, although located on the company property
(f) plumbing, sanitary sewers, and storm sewers.
(g) piping for fire-protection systems
(h) piping covered by applicable governmental regulations

ASME B31.1 – Power Piping Code

This piping code provides requirements for piping typically found in electric power generating stations, in industrial and institutional plants, geothermal heating systems, and central and district heating and cooling systems. This code is mainly important for Power piping professionals. It does not apply to the piping systems covered by other sections of the Code for Pressure Piping, and other piping which is specifically excluded from the scope of this code.

ASME B31.4 – Pipeline Transportation Systems for Liquids and Slurries

This code provides requirements for piping transporting liquids between production facilities, tank farms, natural gas processing plants, plants and terminals, and within terminals, pumping, regulating, metering stations, and other delivery and receiving points.

ASME B31.5 – Refrigeration Piping and Heat Transfer Components

This code prescribes requirements for piping for refrigerants, heat transfer components, and secondary coolants for temperatures as low as -320 degrees F (-196 degrees C)

ASME B31.8 – Gas Transmission and Distribution Piping Systems

This code covers the piping transporting products that are mostly gas (Liquefied Petroleum Gas) between sources and terminals. This code also covers the safety aspects of the operation and maintenance of those facilities.

Other relevant ASME B codes for piping industries are

ASME B31.9 – Building Services Piping
ASME B 31.2 – Fuel Gas piping
AMSE B31.11 – Slurry Transportation Piping Systems.
ASME B31.12 – Hydrogen Piping and Pipelines.

B. ASME Boiler and Pressure Vessel Code

The ASME BPVC code contains 11 sections as mentioned below:

Section I Power Boilers
Section II Material Specifications
Section III Rules for Construction of Nuclear Power Plant Components
Section IV Heating Boilers
Section V Nondestructive Examination
Section VI Recommended Rules for Care and Operation of Heating Boilers
Section VII Recommended Rules for Care of Power Boilers
Section VIII Pressure Vessels
Section IX Welding and Brazing Qualifications
Section X Fiber-Reinforced Plastic Pressure Vessels
Section XI Rules for In-Service Inspection of Nuclear Power Plant Components

Out of these 11 sections, Section VIII is very important for Process Piping engineers.

C. Piping Component Standards

The major piping component standards that are used frequently are listed below:

ASME B16.1: Cast Iron Pipe Flanges and Flanged Fittings
ASME B36.10M: Welded and Seamless Wrought Steel Pipe
ASME B36.19M: Stainless Steel Pipe
ASME B16.9: Factory-Made Wrought Steel Buttwelding Fittings
ASME B16.5: Pipe Flanges and Flanged Fittings
ASME B16.37: Hydrostatic Testing of Control Valves
ASME B16.11: Forged Fittings, Socket Welding and Threaded
ASME B16.3: Malleable Iron Threaded Fittings, Class 150 and 300
ASME B16.4: Cast Iron Threaded Fittings, Classes 125 and 250
ASME B1.1: Unified Inch Screw Threads
ASME B16.20: Metallic Gaskets for Pipe Flanges
ASME B16.21: Nonmetallic Flat Gaskets for Pipe Flanges
ASME B16.25: Buttwelding Ends
ASME B16.10: Face-to-Face and End-To-End Dimensions of Valves
ASME B16.36: Orifice Flanges
ASME B16.34: Valves – Flanged, Threaded and Welding End
MSS SP-58: Pipe Hangers and Supports — Materials, Design, and Manufacture.
BS 6501, Part 1: Flexible Metal Hose
NFPA 1963: Standard for Fire Hose Connections

Refer to ASME code B31.3 for more of the component standards

D. ASTM Standards

The American Society for Testing and Materials (ASTM) is a scientific and technical organization that develops and publishes voluntary standards on the characteristics and performance of materials, products, systems, and services. The standards published by the ASTM include test procedures for determining or verifying characteristics, such as chemical composition and measuring performance, such as tensile strength and bending properties. The standards cover refined materials, such as steel, and basic products, such as machinery and fabricated equipment. The standards are developed by committees drawn from a broad spectrum of professional, industrial, and commercial interests. Many of the standards are made mandatory by reference to applicable piping codes.

The major ASTM standards are listed below:

A36: Carbon Structural Steel
A105: Carbon Steel Forgings, for Piping Applications
A106: Seamless Carbon Steel Pipe for High-Temperature Service
A312: Seamless, Welded, and Heavily Cold-Worked Austenitic Stainless Steel Pipe
A335: Seamless Ferritic Alloy Steel Pipe for High-Temperature Service
A358: Electric-Fusion-Welded Austenitic Chromium-Nickel Alloy Stainless Steel Pipe for High-Temperature Service and General Applications
A516: Pressure Vessel Plates, Carbon Steel, for Moderate and Lower-Temperature Service
A671: Electric-Fusion-Welded Steel Pipe for Atmospheric and Lower Temperatures
A672: Electric-Fusion-Welded Steel Pipe for High-Pressure Service at Moderate Temperatures
Suggested reading for more on ASTM standards: Refer to ASME B31.3 Specification index for Appendix A.

E. API Standards

The American Petroleum Institute (API) publishes specifications, bulletins, recommended practices, standards, and other publications as an aid to the procurement of standardized equipment and materials.

The major ones are listed below for your reference:

API RP 520: Recommended Practice for Sizing, Selection, and Installation of Pressure-Relieving Devices in Refineries.
API 610: Centrifugal Pumps for Petroleum, Petrochemical, and Natural Gas Industries
API 650: Welded Tanks for Oil Storage
API 661: Air-Cooled Heat Exchangers for General Refinery Service
API 560: Fired Heaters for General Refinery Service
API 617: Axial and Centrifugal Compressors and Expander-compressors for Petroleum, Chemical, and Gas Industry Services
API 618: Reciprocating Compressors for Petroleum, Chemical, and Gas Industry Services
API 612: Petroleum, Petrochemical, and Natural Gas Industries-Steam Turbines-Special-purpose Applications

For more API Standards refer to the API website for their catalog of published standards.

There are several other codes and standards which are used in the piping industry including the AMERICAN WATER WORKS ASSOCIATION (AWWA), AMERICAN WELDING SOCIETY (AWS), AMERICAN SOCIETY OF SANITARY ENGINEERS, AMERICAN SOCIETY OF CIVIL ENGINEERS, AMERICAN SOCIETY FOR NONDESTRUCTIVE TESTING, AMERICAN IRON AND STEEL INSTITUTE, EXPANSION JOINT MANUFACTURERS ASSOCIATION, MANUFACTURERS STANDARDIZATION SOCIETY OF THE VALVE AND FITTINGS INDUSTRY, NATIONAL FIRE PROTECTION ASSOCIATION, TUBULAR EXCHANGER MANUFACTURERS ASSOCIATION, etc.

Also, there are non-American standards like BRITISH STANDARDS AND SPECIFICATIONS, RUSSIAN CODES, DIN STANDARDS AND SPECIFICATIONS, JAPANESE STANDARDS AND SPECIFICATIONS, ISO STANDARDS AND SPECIFICATIONS, etc. The user is requested to venture more of these standards in his own interest. Some of the Russian codes are listed below:

F. Russian Codes

GOST 32388-2013 Process Piping Stress Analysis, GOST 32569-2013 Process Piping Design-
These codes provide requirements for process piping design and analysis. GOST 23388-2013 Code covers such aspects as vacuum piping stability, creep in high-temperature piping, cryogenic piping stress analysis requirements, seismic analysis, HDPE piping stress analysis

RD 10-249-98 – Power Piping. Design and Stress Analysis
This code provides requirements for piping typically found in electric power generating stations, in industrial and institutional plants, and geothermal heating systems except for district heating systems.

GOST R 55596-2013 District Heating Systems Stress Analysis, SP 124.13330.2012 District Heating Systems Design
This code provides requirements for buried and above-ground district heating piping systems design and analysis.
SP 36.13330.2012 – Gas and Oil Transmission Piping Systems. Design and Stress Analysis
This code provides requirements for pipelines transporting gas and oil between production facilities, tank farms, natural gas processing plants, plants and terminals and within terminals, pumping, regulating, metering stations, and other delivery and receiving.

GOST 34347-2017 Boiler and Pressure Vessel Code Design Requirements,
GOST 34233-2017 Boiler and Pressure Vessel Code Stress Analysis Requirements
GOST 34233.1-2017: General requirements
GOST 34233.2-2017: Cylindrical and conical shells, convex and flat bottoms and covers
GOST 34233.3-2017: Reinforcement of openings in shells and bottoms under internal and external pressure. Strength calculation of shells and bottoms under external static loads on the nozzle
GOST 34233.4-2017: Strength and leak-tightness calculation of flange joints
GOST 34233.5-2017: Calculation of shells and bottoms under the Influence of support loads
GOST 34233.6-2017: Strength calculation under low-cyclic loads
GOST 34233.7-2017: Heat-exchangers
GOST 34233.8-2017: Jacketed vessels
GOST 34233.9-2017: Vertical Column Vessels
GOST 34233.10-2017: Vessels involving hydrogen sulfide media
GOST 34233.11-2017: Method of strength calculation of shells and bottoms according to weld misalignment, angular misalignment, and shell no roundness
GOST 34233.12-2017: Requirements for representation of the strength calculations carried out on the computer
Piping Component Standards:
Pipes: GOST 10705, 10706, 11068, 2095, 3262, 550, 8696, 8731, 8733, 9940, 9941, 53383, OST series 108x, 34x, TU 14-3-1080, 14-3-1128, 14-3-1160 and lots of other standards
Bends: GOST 17375, 30753, OST series 108x. 34x and lots of other standards
Tees: GOST 17376, OST series 108x. 34x and lots of other standards
Flanges: GOST 33259 and lots of other standards

Stress Analysis of GRP / GRE / FRP Piping System Using Caesar II (ISO 14692)

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

Glass Reinforced Piping (GRP) products, being proprietary, the choice of component sizes, fittings, and material types are limited depending on the supplier. Potential GRP vendors need to be identified early in the design stage to determine possible limitations of component availability. The mechanical properties and design parameters vary from vendor to vendor. Note that the stress analysis methodologies of Fiber Reinforced Piping (FRP) and Glass Reinforced Epoxy (GRE) are similar and performed following the ISO 14692 code. As the design parameters are dependent on the manufacturers, it is of utmost importance that before you proceed with stress analysis of such systems you must finalize the GRP/FRP/GRE vendor.

Several parameters (Fig. 1) for stress analysis have to be taken from the vendor.

Stress analysis of the GRP piping system is governed by ISO 14692 part 3. The GRP material being orthotropic the stress values in axial as well as hoop direction need to be considered during analysis. The following article will provide a guideline for stress analysis of the GRP piping system in a very simple format.

GRP/FRP Information Required from Vendor

Before you open the input spreadsheet of Caesar II communicate with the vendor through the mail and collect the following parameters as listed in Fig.1.

**Fig.1: Parameters required for stress analysis of GRP piping**

The values shown in the above figure are for example only. Actual values will differ from vendor to vendor. The above parameters are shown for a 6” pipe.

Inputs Required for GRP Stress Analysis

For performing the stress analysis of a GRP piping system following inputs are required:

GRP pipe parameters as shown in Fig. 1.
Pipe routing plan in the form of isometrics or piping GA.
Analysis parameters like design temperature, design pressure, operating temperature, fluid density, hydro test pressure, pipe diameter, thickness, etc.

Modeling GRP/FRP/GRE in Caesar II

Once all inputs as mentioned above are ready with you open the Caesar II spreadsheet. By default, Caesar will show B31.3 as the governing code. Now refer to Fig. 2 and change the parameters as mentioned below:

**Fig. 2: Caesar II input spreadsheet for GRP Piping (Simplified Envelope)**

Change the default code to ISO 14692.
Change the material to FRP (Caesar Database Material Number 20) as shown in Fig. 2. It will fill a few parameters from Caesar’s database. Update those parameters from vendor information.
Enter pipe OD and thickness from vendor information.
Keep corrosion allowance as 0.
Input T1, T2, P1, HP, and fluid density from the line list.
Update pipe density from the vendor information sheet, if the vendor does not provide the density of the pipe then you can keep this value unchanged.
On the right side below the code, enter the failure envelope data received from the vendor.
Enter thermal factor=0.85 if the pipe is carrying liquid, and enter 0.8 if the pipe carries gas.
After you have mentioned all the highlighted fields proceed to model by providing dimensions from the isometric/piping GA drawing. Add supports at the proper location from the isometric drawing.
Now click on the environment button and then on the special execution parameter. It will open the window as mentioned in Figure 3.

**Fig. 3: Typical Special Execution parameters Spreadsheet.**

Now Refer to Fig. 3 and change the highlighted parts from the available data.

Enter the GRP/FRP co-efficient of thermal expansion received from the vendor
Calculate the ratio of Shear Modulus and Axial modulus and input in the location.
In FRP laminate keep the default value if data is not available.
After the above changes click on the ok button.
While modeling, remember to change the OD and thickness of elbows/bends.

Modeling of GRE Bend and Tee Connections

The modeling of bends is a bit different as compared to CS piping. Normally, bend thicknesses are higher than the corresponding piping thickness. Additionally, you have to specify the parameter, (EpTp)/(EbTb), which is located at the Bend auxiliary dialogue box as shown in Fig. 4. This value affects the calculation of the flexibility factor for bends.
When you click on the SIF and Tee box in the Caesar II spreadsheet, you will find that only three options (Tee, Joint, and Qualified Tee) are available for you, as shown in Fig. 4. Each type has its own code equation for SIF calculation. Use the proper connection judiciously. It is always better to use SIF as 2.3 for both inplane and outplane SIF to adopt a maximum conservative approach.

Modelling of Elbows and Tees for FRP/ GRE piping — **Fig. 4: Modelling of Elbows and Tees for FRP/GRE piping**

Stress Analysis Load Cases for FRP Piping Systems:

ISO 14692 informs to prepare 3 load cases: Sustained, Sustained with thermal, and Hydro test. So accordingly, the following load cases are sufficient to analyze the GRP piping system

WW+HP …………………….HYDRO
W+T1+P1 …………………..OPERATING-MAXIMUM DESIGN TEMPERATURE
W+T2+P1 …………………..OPERATING-OPERATING TEMPERATURE
W+T3+P1 …………………..OPERATING-MINIMUM DESIGN TEMPERATURE
W+P1 ………………………..SUSTAINED

Here,

WW: Water-filled weight
HP=Hydrotest pressure
T1=Maximum design temperature
T2=Maximum operating temperature
T3=Minimum design temperature
P1=Design pressure, and
W=Content filled pipe weight

The expansion load cases are not required to be created as no allowable stress is available for them as per the code.

Note that, sometimes GRE piping network may have slug scenarios when carrying two-phase liquids. Again, they may have surge scenarios like firewater GRE pipe networks. So, those forces, if any, need to be considered additionally, as the case may be.

Again, if you are analyzing a piping system consisting of GRE pipe plus metallic piping, then expansion load cases need to be prepared.

While preparing the above load cases you have to specify the occasional load factors for each load case in the load case options menu as shown in Fig. 5. ISO 14692 considers hydro test case as an occasional case. In higher versions of Caesar II software (Caesar II-2016 onwards), these load factors are taken care of by default. So you need not enter the values. The option of these value entries will be available only if you define the stress type as occasional for those software versions.

**Fig. 5: Specifying Occasional Load factors in Caesar II for GRP/FRP piping system**

The default values of occasional load factors are 1.33 for the occasional case, 1.24 for the operating case, and 1.0 for the sustained case. These occasional load factors are multiplied with the system design factor (normally 0.67) to calculate the part factor for loading f2.

For aboveground GRP piping, the above load cases are sufficient. But if the line is laid underground, then two different Caesar II files are required. One for sustained and operating stress checks. The other is for hydro testing stress check as the buried depth during hydro testing is different from the original operation. Also, buried depth may vary in many places. So, Caesar II modeling should be done meticulously to take care of the exact effects.

For buried GRP pipe modeling, one needs to split the long lengths into shorter elements to get proper results. An element length of 3 m or less is advisable. Sometimes buried model contains a pipe slope, Those slopes are required to be modeled properly to get accurate results.

Code Stresses as per ISO 14692-2005

ISO 14692 2005 requires that the sum of all hoop stresses (σ_h, sum) and the sum of all axial stresses (σ_a, sum) be evaluated for all states of the piping system. CAESAR II evaluates these stresses for stress types OPE, SUS, and OCC. If the hoop stress is exceeded, the axial stress is not reported.

There are two stress envelopes in ISO 14692; Fully Measured Envelope and Simplified Envelope.

Stress Equations as per the Fully Measured Envelope

For Fully Measured Envelope; the inputs of σ_hl(1,1) and σ_al(1,1) are required in the piping input spreadsheet. The equations used in Caesar II software when analyzing using a fully measured envelope are as follows:

**Fig. 6: Code Equations for Fully Measured Envelope**

Stress Equations as per the Simplified Envelope

For Simplified Envelope, the inputs of σ_hl(1,1) and σ_al(1,1) are not required in the piping input spreadsheet. The equations used in Caesar II software when analyzing using a simplified envelope are as follows:

**Fig. 7: Code Equations for Simplified Envelope**

Explanation of the symbols used in the above equations:

The significance of the symbols that are used in the above-mentioned equations are:

f₂ = Part Factor for Loading
- 0.89 for Occasional Short-Term Loads
- 0.83 for Sustained Loads Including Thermal Loads
- 0.67 for Sustained Loads Excluding Thermal Loads
A₁ = Partial Factor for Temperature
A₂ = Partial Factor for Chemical Resistance
A₃ = Partial Factor for Cyclic Service
σ_qs = Qualified Stress (entered for bends, fittings, and joints)
σ_al(0,1) = Long-Term Axial Strength at 0:1 Stress Ratio
σ_al(1,1) = Long-Term Axial Strength at 1:1 Stress Ratio
σ_hl(1,1) = Long-Term Hoop Strength at 1:1 Stress Ratio
σ_al(2,1) = Long-Term Axial Strength at 2:1 Stress Ratio
σ_hl(2,1) = Long-Term Hoop Strength at 2:1 Stress Ratio
r = Bi-Axial Stress Ratio 2σ_al(0,1)/σ_qs (for simplified and rectangular envelopes)
σ_a,sum = Sum of All Axial Stresses {(σ_ap + σ_ab)² + 4ξ²}^1/2
σ_h,sum = Sum of All Hoop Stresses [σ_h² + 4ξ²]^1/2
σ_ap = Axial Pressure Stress
σ_ab = Axial Bending Stress
ξ = Torsion Stress
σ_h = Hoop Stress

Note that, in the year 2017, ISO 14692 received a new update, and there are many changes, which are explained here: What’s new in ISO 14692-2017?

Output Results from GRP Stress Analysis

Both stress and load data need to be checked for GRP piping. Normally the stresses are more than 90% (Even, sometimes it may be as high as 99.9%).

Few more related articles for you.

Stress Analysis of GRP / GRE / FRP Piping using START-PROF
What’s new in Revised ISO 14692: 2017 Edition
HYDROSTATIC FIELD TEST of GRP / GRE lines
Stress Analysis of GRP / GRE / FRP piping system using Caesar II
A short article on GRP Pipe for beginners

Online Video Course on FRP Pipe Stress Analysis

I have prepared a dedicated online course for explaining the steps followed in FRP/GRP/GRE pipe stress analysis using Caesar II.

Pre-Commissioning and Commissioning Checklist for Flare Package

Written by Anup Kumar Dey in Mechanical

Importance of Flare

All of you are aware that the flare is the last line of defense in the safe emergency release system in a refinery, chemical, petrochemical, or pharmaceutical plant. It uses to dispose of purged and wasted products from respective plants, unrecoverable gases emerging with oil from oil wells, vented gases from blast furnaces, unused gases from coke ovens, and gaseous water from chemical industries. So its design and construction have to be accurate and quality must be maintained.

Why use a Checklist for the Flare Package?

Checklists are very important tools for improving the quality and accuracy of any job. It helps engineers and designers to verify all important points while carrying out any work. It helps to reduce failure by compensating for the potential limits of human memory and attention. Any engineering design activity can be verified for accuracy, consistency, and completeness using a checklist. Checklists are an important document for quality audits. They are important in every task.

This checklist will highlight a few important points that should be checked before the commissioning of any flare packages. This list is not exhaustive, Readers are requested to add more points in the comments section.

Pre-Commissioning Checklist

The tag number and location coincide with the P&ID drawing number.
Check the Equipment visually for defects if any.
Confirm whether the vendor representative should be available for the commissioning
Check the equipment layout, and nameplate rating, and ensure conformity to specification.
Inspect and ensure the correct assembly of the equipment with the vendor P&ID
Check the insulation, if required, has been applied in accordance with the specification.
Check the suitability of flanges, facing, and gaskets for service conditions.
Check the alignment record of the equipment. All records should have the signature of the Owner’s Construction Representative.
Remove all temporary construction materials, facilities, and equipment.
Confirm that equipment grounding has been properly installed.
Confirm that all instruments have been installed in their proper locations
Confirm the equipment pre-commissioning/ commissioning procedure is available from the vendor and that operating personnel is thorough with the procedure.
Check the installation and support of all piping to ensure against vibration and fatigue in operation.

Provide scaffolding, safety lines, and barriers. Rope off the working area to keep out unauthorized personnel.
Check the inspection records of equipment.
Confirm that access ladders are properly fitted and fastened to the support clips provided
Check platforms have been installed to allow safe access to all valves and instrumentation that is located on the skid and they have been fitted with guard rails
Confirm that all connecting piping and valves have been installed on the skid, including isolation, control, instrumentation, and relief. Also, confirm that all instruments (local and those with transmitters) are properly installed.
Clean out all debris and test all drain systems free and clear, ready for start-up.
Check all operating blinds are installed as detailed in the drawing.
Remove all temporary construction materials, facilities, and equipment.
Confirm that the Manufacturer’s Test Certificate is available and that the information on the skid nameplate agrees with the certificate and is legible.
Confirm that the final external paint coating has been applied
Wherever applicable vessel, piping, pump, tank, the checklist should be applied.

Commissioning Checklist

Operational testing of the equipment including leak testing (at maximum operating pressure) Is carried out.
Operational and functional testing of instrumentation, control, and safety systems, including loop checking logic checking, operational testing of DCS/ESD systems, and package control systems.
Testing of CP system and all electrical power systems equipment, all motor runs, and test on lighting, power, and earthing systems. Energizing of switchboards and transformers
PSV inlet and outlet valves open and by-pass valves closed.
Check all the drain and vent valves.
The procedure for the start-up as per the Operating manual is clear to the Operator

Few more useful Resources for you…

Routing Of Flare And Relief Valve Piping: An article-Part 1
Flare systems: Major thrust points for stress analysis
Stress Analysis of PSV connected Piping Systems Using Caesar II
Articles related to Process Design
Piping Layout and Design Basics
Piping Stress Analysis Basics

Overview of Piping and Instrument Interface

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

The main function of instrumentation in every process plant is to collect intelligence from the working plant and use those data to control the process parameters as per predefined conditions. Instruments in piping measure different process conditions like pressure, temperature, flow, density, and level as per the process requirement.

Piping engineers have a thorough interface with the instrumentation team for knowing the details of the instruments used. The main responsibilities as part of the instrument-piping interface are modeling these instruments in the 3D models at proper locations and providing appropriate access for operation and maintenance. While pipe-routing, special layout requirements near the instruments for their proper functioning must be ensured.

The instrumentation team provides instrument hook-up drawings explaining how a particular instrument is connected to the piping. The main interface with piping components, special requirements like upstream and downstream straight length requirements, connection types, valve types, access and maintenance requirements, instrumentation-piping scope demarcation, etc are provided clearly in the instrument hook-up drawings. Other deliverables to the piping department from the instrumentation team are:

Control valve datasheets.
Preliminary Instrument dimensional drawings and datasheets.
PSV sizing and reaction forces.
Panel and Other accessory details.

Piping has a regular interface with the Instruments for

Scope Break
Process Connections
Materials and BOM
Orientation

The interfaces are mostly standardized. However, these should be discussed with the C&A (Control and Automation or Instrumentation) team at an early stage of the project, preferably.

Some instruments give desired performance when installed in a particular position/orientation. (ex: Coriolis meter). When in doubt the functionality of the instrument should be discussed with the C&A engineer.

Types of instruments

Instruments in the piping industry can be classified into the following three groups:

In-line Instruments
On-line Instruments, and
Offline Instruments

In-line instruments:

In-line instruments are considered to be all instruments and components direct-mounted in or on process and utility lines or equipment and are subjected to the pressures and temperatures of the piping systems or equipment in or on which they are installed. Examples of a few inline instruments are given below.

On-line instruments:

On-line instruments are all instruments and components connected to process and utility lines or equipment via small (maximum DN 50 or 2 in) primary isolation valves. They are subjected to the pressures of the piping systems or equipment on which they are installed.

Typical examples of online instruments are impulse line components, transmitters, pressure gauges, mono-flange assemblies, analyzer sampling systems, etc.

Offline instruments:

Off-line instruments are considered to be all instruments and components, which are not in direct, contact with any process medium or which are not connected to any process/utility line or equipment

Typical examples of offline instruments are thermocouples, resistance elements, bi-metallic thermometers in thermowell, signal converters, local receiving indicators, etc.

Piping-Instrumentation Interface Salient Points

Some general points which need to be remembered are mentioned below:

Datasheets for ESD valves if not standardized the Plant ESD valve datasheet must be given to C&A
Material details for the control valves, Nuts, Bolts, and Gaskets should be considered by piping. Flanges as per ASME B 16.5
A process-to-instrument valve unit is a means of interfacing between process piping and instrumentation systems.
Instrument specifications apply downstream the last joint of the last process to the instrument valve or valve assembly, defined for the instrument connection in the mechanical piping class.
The philosophy is to use single-block valves up to Class 600 and a double block for Class 900 and above.
If the pipe is insulated, then the design shall incorporate an “over the insulation design” or mount the transmitter remotely.

Flow Instruments:

Flow meters measure the flow. There are various types of flowmeters that can be used in a piping system. Click here to learn more details about flowmeters and their types and applications.

1. Coriolis Flowmeter:

Should be installed on the downside In Liquid Service and upside in Gas service
Flow direction should be marked on vendor drawings
Orientation should be shared with C&A.

2. Vortex / Ultrasonic Flowmeter / Restriction orifice (Fig. 3)

Straight lengths should be maintained.
Tappings on the straight length should be avoided

3. Flow Transmitters / Restriction orifice (Fig. 4)

Break at the isolation valve ( DBB /SBB).
The end connection ( instrument side) should be discussed. ( generally threaded)

Analytical Instruments

1. Red Eye Meter (BSW meter-Fig. 5)

Orientation is to be ensured in such a way that the instrument is always flooded.
Flow direction should be marked on vendor drawings
Orientation should be shared with C&A

Pressure Instruments

Pressure instruments measure the pressure difference. They are popularly known as Pressure gauges or Pressure Transmitters. Click here to learn more about pressure-measuring instruments.

Pressure Gauge / Pressure Transmitter-Break at the isolation valve ( DBB /SBB).

Level Instruments

Level instruments are also known as Level Gauges or Level transmitters. Click here to learn more about Level gauges. The main points related to the piping-instrumentation interface for level gauges or level transmitters are:

Break at the Isolation valve
Drain / Vent valve under the piping scope
Level gauge drawings by piping
Transmitter details by C&A

Temperature instruments

Temperature instruments measure the temperature. Thermowells are the most widely used temperature-measuring instruments in the piping industry. Click here to know details about thermo-wells. The instrument-piping interface’s salient points are:

Scope break at the flange.
Gaskets, studs, bolts by piping

API 610 Pumps vs ANSI / ASME B73.1 Centrifugal Pumps

Written by Ankur Srivastava in Mechanical,Process

ANSI Pump and API Pump are two types of Centrifugal pump styles that are used in Chemical Plants, Refineries, and Oil and Gas Industries. They have some distinct differences. This article will compare the major features of both these pumps.

What is an API Pump?

An API Pump is a special type of centrifugal pump that meets the design, inspection, and testing criteria specified by the American Petroleum Institute’s API-610 standard for pumps. In Refineries and Petrochemical Industries, mostly API pumps are used as they provide very good operating experience in handling hydrocarbons (oil, gasoline, Natural gas, and petroleum products) due to their robust design. Generally, They come in many different forms employing a number of pumping mechanisms. Traditionally API pumps are considered very conservative (stringent) and costly.

What is an ANSI Pump?

ANSI Pumps are a type of horizontal, single-stage, end suction centrifugal pump that has an overhung impeller and back pull-out. This type of pump is designed based on the ASME B73.1 standard. Due to their low cost, they are popularly used in chemical industries, refineries, and industrial and mining applications for comparatively less temperature pressure applications. The main advantage of ANSI pumps is their interchangeability across manufacturers and brands.

ANSI Pump vs API Pump

Compared to an API pump, the typical ANSI pump has the following characteristics:

Criteria	API Pump	ANSI Pump
Design Code	API 610	ASME/ANSI B 73.1
Pump Casing	Thick Casing, more corrosion allowance. In general, designed for 750 PSIG at 500℉.	Thinner Casing, less corrosion allowance. Normally designed for 300 PSIG at 300℉.
Nozzle Load	More sensitive to pipe-induced stresses, ANSI pumps allow reduced permissible nozzle load	More sensitive to pipe-induced stresses, hence ANSI pumps allow reduced permissible nozzle load
Stuffing Box Size	API pumps have a large Stuffing Box.	Smaller stuffing box size. Unless a large bore option is chosen, an ANSI pump may not be able to accommodate the optimum mechanical seal for a given service.
Impeller Design	API pumps feature closed impellers with replaceable wear rings.	ANSI pump impellers are designed and manufactured without wear rings. Many ANSI pump impellers are open or semi-open
Mounting Option	Normally, API pumps are center-line mounted	Generally, ANSI pumps are foot-mounted.
Application	API pumps are suitable for heavy-duty, much higher temperatures, and pressures	ANSI pumps are usually not suitable for moving thicker and/or viscous fluids. Moderate duty application.
Reliability	API pumps are highly reliable	The reliability of ANSI pumps is comparatively less.
Cost	High	Comparatively less

Difference Between API Pump and ANSI Pump

Refer to the attached sketch. In foot-mounted pumps, casing heat tends to be conducted into the mounting surfaces and thermal growth will be noticeable. It is generally easier to maintain the alignment of API pumps since their supports are surrounded by the typically moderate-temperature ambient environment.

Choosing Pump Type: API or ANSI

The decision on API vs. ANSI construction is experience-based and is not governed by governmental or regulatory agencies. However, experienced machinery specialists have their own likes and dislikes based on the experience gathered by them over their long years in the machinery field.

Many highly experienced and reliability-focused machinery engineers would prefer to use pumps designed and constructed according to API 610 for toxic, flammable, or explosion-proof services at on-site locations in close proximity to furnaces and boilers in some of the conditions (rules-of-thumb) that are listed below:

Head exceeds 106.6 m (350 ft)
The temperature of pumpage exceeds 149°C (300°F) on pumps with discharge flange sizes larger than 4 inches or 177°C (350°F) on pumps with a 4-inch discharge flange size or less.
Driver horsepower exceeds 74 kW (100 hp)
Suction pressure in excess of 516 kPag (75 psig)
Rated flow exceeds flow at best efficiency point (BEP)
Pump speed in excess of 3600 rpm.

The author mentions that there have been exceptions made where deviations from the rules-of-thumb were minor, or in situations where the pump manufacturer was able to demonstrate considerable experience with ANSI pumps under the same, or even more adverse conditions.

Finally, the author gives his opinion on choosing either API or ANSI pumps based on the following:

Conventional Wisdom: API-compliant pumps are always a better choice than ANSI or ISO pumps

Fact: Unless flammable, toxic or explosion-prone liquids are involved, many carefully selected, properly installed, operated and maintained ANSI or ISO pumps may represent an uncompromising and satisfactory choice.

The above comparison that is provided in the article is referenced from Heinz P. Bloch’s book “Pump User’s Handbook Life Extension” co-authored with Allan R. Budris.

Few more useful resources for you.

Pump Suction Intake Design with Sample Calculation
Pumps & Pumping Systems: A basic presentation
Stress Analysis of Water Pump Station Piping using Flexible Sleeve Coupling
Types of Pumps used in Process Plants
Cause and Effect of Pump Cavitation

Selection of Pipes for a Plant: Pipe Selection Guidelines

Written by Anup Kumar Dey in Engineering Materials,Piping Design Basics

Proper pipe selection for a plant is really a difficult task. Organized efforts of Metallurgist and Process Engineers are required for proper pipe selection. There are two approaches to pipe selection that are normally followed in industries.

Selection of Pipe by Pipeline Approach

When pipelines and production facilities are being built the emphasis is placed on the pipe wall thickness. Generally, there is a great amount of pipe, and quantities of fittings and valves are small by comparison. Minimizing the pipe wall is the major economic factor. The extra cost of custom-made fittings is far outweighed by the savings on the pipe. The pipe is purchased by weight, so the added cost of high-strength material to lower the pipe wall is a reasonable consideration. When high-strength material is specified, extra inspection and more stringent interpretation are also necessary. The cost of the extra inspection is also a reasonable consideration. Spare parts warehousing is a small consideration.

Plant Pipe Selection Approach

When plants are built, the pipe selection emphasis is on standardized materials. The design is such that materials made to the specified standard are adequate for the service. Certain specific services may require additional inspection or special requirements, but these are for service, and not economics.

Materials are usually purchased from warehousing companies. The relative cost of pipe is a considerably smaller percentage of the total cost, compared with pipelines. The cost of machinery and equipment takes a large part of the budget. The cost of fittings and particularly valves make up a large part of the whole piping budget. The easy, and quick procurement of spare, and replacement parts, becomes very important. Pipe walls may be bumped up, if the quantity is small, to a greater thickness that is more available or already specified in large quantities. There is a price vs. availability relationship that is easy to overlook.

Pipe Selection Guide: Price vs. Availability

The price vs. availability relation can be shown by the following examples. Type 304 stainless steel costs less than type 316. Many valve manufacturers standardize on type 316 because it is generally suitable for type 304, and 316 services. If type 304 is the only choice, a valve will have a higher price and extended delivery. Even if the price is the same, the lack of availability can slow a project.

The actual material is normally specified by the process licensor, company, or project metallurgist, or is part of the Process Package. The selection of pipe is limited by the design condition and specific service as mentioned below:

Design Limitations while piping selection

Pipe Material:

Pipe material is defined by material, type of joint, joint efficiency, wall thickness, etc. The pipe has a material name. Typical names are carbon steel, stainless steel, and chrome-moly steel. The pipe has a material type. Typical types within the material names are killed steel, low-temperature carbon steel, carbon steel, austenitic stainless steel, ferritic stainless steel, type 316 stainless steel, 11/4 Cr – 1/2 Mo, and so on.

The pipe has a manufacturing standard. Typical material standards for pipe are ASTM A106, API 5L, ASTM A333, and ASTM A671, for carbon steel, ASTM A312, and ASTM A358, for stainless steel, and ASTM A355, and ASTM A691. Again each Pipe has a material grade. Typical grades are Grade B, X60, TP304, and Gr 11/4 Cr.

Pipe Sizes:

The outside diameter of the steel pipe shall be in accordance with API Spec 5L Table 6.2. Intermediate sizes and the sizes NPS 1/8, 1/4, 3/8, 1-1/4, 2-1/2, 3-1/2, and 5 shall not be used except when necessary to match equipment connections. In this case, a suitable transition shall be made as close as practical to the equipment.
The minimum allowable pipe size, including vents and drains, is NPS 3/4.

Wall Thickness of Pipe:

The standard for Wall Thickness: Wall thickness may be expressed as wt, std, xs, and XXS, schedule, and plate thickness. Weight classes and schedules are defined in ASTM A53.
Pipe Made From Plate: A pipe made from a plate shall have the wall thickness expressed in mm.
Minimum Wall Thickness: The minimum wall thickness for the pipe is generally the minimum thickness that will stand under its own weight, with minimum deflection. Wall thickness is always calculated for the design temperature and pressure, in accordance with the appropriate ASME B31 code.
Wall Thickness Standardization: Wall thickness standardization is necessary to minimize stocking requirements, and take advantage of quantity pricing. In the plant approach, the pipe is not specified in a vacuum. The pipe is welded to flanges and fittings in relatively large quantities. The major criterion in pipe wall selection may not be from temperature and pressure, but from the availability of fittings and flanges. Piping is a system, and other items must be considered during selection. When a pipe is made from a plate, the accompanying fittings may be in a special order, and affect the critical path.

Piping End Connections:

Threaded End Pipe: Threaded pipe shall be provided threaded and coupled.
Pipe for Socket weld Systems: Pipe intended for socket welding shall be square cut.
Butt-welding Ends: Butt welding ends shall be in accordance with the requirements of ASME B16.25.

Lengths: Pipe shall be supplied in double random lengths.

Galvanizing: Galvanizing shall be applied in accordance with ASTM A53.

Pipe Joints:

Seamless Pipes:

Wrought Pipe: Seamless pipe is made by extrusion, or by piercing and rolling
Casting: Cast pipe suitable to be qualified as seamless must be centrifugally cast.
Forging: Seamless pipe can be made by the forging and boring process.

ERW Pipe:

ERW pipe is Electric Resistance Welded. In this process, a flat plate is formed into a cylinder and put through energized rollers that press the seam together and provide a resistance weld. ERW pipe has reduced allowable than seamless.

EFW Pipe:

Electric Fusion Welded Pipe: EFW pipe is rolled into a cylinder and welded with filler material. This is a fusion weld and may be qualified to several levels.
DSAW: Submerged Arc Welding is a common form of EFW. Depending on thickness, the manufacturing standard calls for a single or double weld. The thinner walls are welded outside, and thicker walls are welded inside and outside, hence Double Submerged Welding, or DSAW.
Type-F: Furnace butt-welded pipe, also known as type F, is used in petrochemical applications only for water.

Straight Seam:

Straight seam refers to a straight seam parallel to the longitudinal axis. The hoop stress has no component in the axial direction. A straight seam is made by drawing a plate through a series of rollers to make it a cylinder, for welding.

Spiral Seam:

A spiral welded pipe is made in a special machine that takes coiled steel and rolls it into a spiral, which is welded into a pipe. This is a relatively continuous process. The machine makes it relatively easy to change pipe size. The convertibility of the machine and the limited stock required make this machine ideal for local production. Spiral welded pipe is not readily accepted in the industry for other than water, despite the favorable cost, and recent tightening-up of the standard.

Joint Efficiency of Pipe:

All pipes that are not seamless are subject to joint efficiency. The committees that publish the codes place a restriction on the allowable stress for the welded pipe. This restriction is in the form of a joint efficiency, clearly stated in the codes.
A pipe can be qualified for higher joint efficiency by inspection. The major factor is radiography. The type and extent of radiography are listed in the codes.

Special Requirements during pipe selection

There may be special requirements for the base material, fabrication, or inspection. These special requirements shall be clearly indicated in the Purchase Description.

Mill Test and Chemical Analysis Report:

A certified mill test and chemical analysis report shall be submitted by the Seller of all alloy pipe (including ASTM A333), and all pressure-containing alloy piping components made from pipe not clearly marked in accordance with MSS SP-25.
A certified mill test and chemical analysis report are also required for carbon steel pipe, nipples made from pipe, swages, and all pressure-containing carbon steel components made from pipe not clearly marked in accordance with MSS SP-25, for use in ASME Section I or ASME B31.1 piping systems.
When alloy material and carbon steel, as noted above, are purchased by an outside shop pipe spool fabricator, the fabricator shall obtain these reports.

Piping Nipples:

Pipe Nipples with schedule 160 shall be installed in sizes NPS 2, and smaller pipe sizes in vibration service where bracing cannot be effectively provided.

Piping Material Classes:

The piping material classes in these standards show the actual selections for piping, as well as all piping materials, by example. The classes show pipe and all of the associated materials for each service. These classes are to be used as a basis for new services.

Pipe Selection with Specific Service Limitations

Carbon Steel Pipes:

Carbon steels are used in a variety of cases.

Low-Strength Steel: Low-strength steels are generally only used for open piping, such as gravity sewers.
Regular Steel: Regular steels are used for general service, including water, and hydrocarbons. These are services with no special requirements.
Low-Temperature Carbon Steel: Low-temperature carbon steel is steel that has been killed to improve the microstructure to raise the fracture toughness, to reduce susceptibility to brittle fracture. Low-temperature carbon steel must be qualified by impact testing.
Killed Steel: Killed steel has the same improved microstructure as low-temperature carbon steel, but the improved microstructure reduces susceptibility to sulfide cracking, as well as other related cracking. The fine grain structure and quality of structure also provide resistance to hydrogen attack.
NACE: When a pipe is to be used in wet H₂S, NACE MR0175 is invoked to assure resistance to sulfide cracking, including the use of killed steel.
High-Strength Steel: High-strength steels are generally not approved for use under ASME B31.1 and B31.3. only the lowest grades are listed. High-strength steels are used in pipeline service to reduce the pipe wall.

Chrome alloys:

Corrosion Resistance: Chromium alloy steel also uses molybdenum to control the microstructure. Corrosion resistance is improved.
Hydrogen Resistance: Generally, chrome and Molybdenum are added for hydrogen resistance. The Nelson Curves show the relationship between the partial pressure of hydrogen, temperature, and chrome content. The curves are found in API 941.
High Strength: The addition of chrome also improves high-temperature strength.
High Temperature: Steam will cause graphitization in carbon steel at temperatures over 425 deg. C and chrome steel is recommended.

Stainless Steel Pipes:

Stainless Steel Types: Stainless steel offers resistance to corrosion in three ways. Higher percentages of Chromium offer corrosion resistance, as an alloy. Higher percentages of chrome with nickel alter the microstructure from ferrite to austenite. The austenite offers corrosion protection. Certain compositions will produce what is known as duplex steel, which exhibits the qualities of ferritic and austenitic steels.
300 Series Steels: The 300 series steels are the most common. There are two basic subtypes, in which the austenite is stabilized, or not. The most common types are type 304 and type 316. These materials exhibit microstructure problems at various temperatures. The austenite can be stabilized with Titanium, and Columbium (Niobium). These grades are type 321 and 347. A metallurgist is required to make the determination. 300 series stainless steels are extremely susceptible to chloride stress cracking.
400 Series Steels: The 400 series steels are less available, and are more difficult to work with. These steels are generally only specified for specific fluid conditions. 400 series steels offer less corrosion resistance than 300 series. Ferritic stainless steel offers better abrasion resistance than the 300 series.
Duplex Steels: Duplex stainless steels have the corrosion resistance of the 300 series, and the abrasion resistance of the 400 series, and are not subject to chloride cracking.

Other Materials:

Some of the materials below are represented by the proprietary name for clarity.

Monel: Monel is a copper-nickel alloy that is usually used around caustic, at higher temperatures. Monel is not readily available, particularly valves.
Alloy 20: Alloy 20 is a proprietary name, but most alloys have similar names. Alloy 20 is most used in acid services.
Nickel Alloys: Nickel alloys such as Incoloy and Inconel are proprietary, and are used for high-temperature services.

Pipe for Pipelines:

With the pipeline approach, the material is usually high strength. The specific composition of the metal depends on the makeup of the fluid carried. The limitations on composition vary, so there is a separate specification specifically for line pipe. Schedule 40 is usually considered the minimum pipe wall, for mechanical strength, in small sizes, NPS 10 and smaller. When the pipe wall calculates at or below Sch 40, regular strength material is a considerable cost saving.

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