PIPING DESIGN BASIS
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06.12.2007
REV.
DATE
PREPARED BY
Onshore Engineering Services New Delhi PROJ: Assam Renewal Project Job No.: OESG-AA-07-001
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PIPING DESIGN BASIS
APPROVED APPROVED BY
DOCUMENT NO.: OESG/ARP/DB/0006
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1.0
SCOPE This specification covers the basis for the overall design of process and utility piping system and should be read in conjunction with piping scope of work, and piping specifications enclosed in this document. The requirements given in this specification are minimum. Contractor shall be responsible for ensuring that the design of piping system conforms to codes and accepted practices currently applicable to piping system.
2.0
CODES AND STANDARDS The latest versions of the main design codes and standards as listed below shall be considered as minimum requirements. ASME B 31.3
Chemical Plant And Petroleum Refinery Piping
ASME BPV
Boiler and pressure vessel code.
IBR
Indian Boiler regulations.
API AP 520
Sizing, selection and installation relieving devices in refineries.
ASME SEC VIII
Pressure Vessel
OISD-118
Layouts for oil and gas installation
ASME B 31.1
Power Piping
ASME B 31.5
Refrigeration piping.
of
pressure
In addition to the above, piping specifications together with various international and National Codes and Standards referred therein shall be applicable. 3.0
DESIGN CRITERIA
3.1
DESIGN TEMPERATURE Minimum and maximum design temperature shall be determined in accordance with the provisions of ASMEB 31.3 and shall in no case be less severe than those specified.
3.2
DESIGN PRESSURE The design pressure of piping shall be determined in accordance with the provisions of ASMEB 31.3 and in no case shall be less than the following: a) 3.5 Kg/Cm2 b) Design pressure of the equipment to which the piping is connected. Onshore Engineering Services New Delhi PROJ: Assam Renewal Project Job No.: OESG-AA-07-001
PIPING DESIGN BASIS
DOCUMENT NO.: OESG/ARP/DB/0006
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c) Set pressure of safety valve, which protects the system. d) For piping at the discharge of centrifugal pump, it shall be higher of •
•
1.2 times the maximum pump differential pressure plus the maximum suction pressure. Total shut off pressure plus the maximum suction pressure.
e) Design pressure for piping systems operating under vacuum shall be full vacuum. 3.3
ALLOWABLE STRESSES These shall be determined in accordance with ASMEB 31.3.
3.4
OTHER CONDITIONS a) Loads Affecting Piping Stresses Various loading significantly affecting piping stresses shall be considered in accordance with ASMEB 31.3 and shall include ambient effects, dynamic effects (impact, wind, earthquake, vibration), weight effects (live and dead). Thermal expansion effect, load of bare pipe+fluid+insulation(if any), load of valves, online equipments and instruments, loads due to internal pressure, steam out condition(if any), any external loads/concentrated load etc. b) Piping Flexibility analysis criteria All piping must be designed and analyzed for thermal expansion, contraction, relief valve reaction, under start-up, operating and shut down conditions without over stressing the piping, valves or equipments. Expansion joints shall not be used for arresting thermal stresses unless otherwise specified or approved by owner. Provisions for expansions or contraction shall normally be made with bends & offsets. Expansion joints may be used on large diameter piping relief systems or where they are acceptable process wise provided they are designed for minimum 7000 cycles. Forces and moments due to weight, thermal loads and other imposed loads on the equipment nozzle must not exceed the allowed loads for the equipment.
c) Piping Supports criteria
Onshore Engineering Services New Delhi PROJ: Assam Renewal Project Job No.: OESG-AA-07-001
PIPING DESIGN BASIS
DOCUMENT NO.: OESG/ARP/DB/0006
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All piping shall be adequately supported, guided or anchored so as to prevent undue vibration, deflection/expansion or loads on connected equipment & piping and leakage at joints. Piping at valves and equipment such as heat exchangers and pumps, requiring periodic maintenance shall be supported in such a way so that the valves and equipment can be removed with a minimum necessity of installing temporary pipe support. Additional supports, guides, anchors, special supports like spring support and sway braces shall be provided after detailed analysis of piping system to restrict the forces experienced on nozzles of critical items like pumps, compressors, turbines, exchangers, etc. the supports shall be indicated in the piping GAD’s and isometrics as applicable. Suitable supports shall be provided for lines, which do not need any, support, but otherwise become unsupported by opening of flange etc. for maintenance and thus may transfer load on attached equipment, etc. For pulsating flow lines, detailed thermal and vibration analysis by analog study shall be done to decide the location of anchor supports and guides, etc. 3.5
CORROSION ALLOWANCE Unless otherwise specified in piping material specification the following corrosion allowance shall be provided as a minimum in all process and utility systems: Carbon Steel
:
1.5 mm
Ferritic Alloys
:
1.5 mm
Austenitic steel
:
NIL
Non Ferrous
:
NIL
For IBR piping refer to the requirements under the IBR regulations. 3.6
PIPE WALL THICKNESS AND REINFORCEMENT Wall thickness and reinforcement shall be determined in accordance with ASMEB 31.3. Proper corrosion allowance and mill tolerance shall be considered to achieve the selected thickness.
3.7
LINE AND CONNECTION SIZE Minimum line sizes shall be as per approved P&ID's prepared by the Contractor. Minimum line size within process plant area shall be 1" and 2" for long runs in the offsite area except for instrument tubing and steam Onshore Engineering Services New Delhi PROJ: Assam Renewal Project Job No.: OESG-AA-07-001
PIPING DESIGN BASIS
DOCUMENT NO.: OESG/ARP/DB/0006
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tracer, which may be minimum ¼" and ½" respectively. Vents and drains shall be ¾" minimum. Pipes sizes such as 1-¼". 2-½", 3-½", 5", 7" and 9" shall not be used except where required for connections to mechanical equipment of standard design or where specified velocities must be maintained. 3.8
BENDS AND MITRES a)
Long radius welding elbows shall be used in general for changes in direction of piping. For steam and feed water piping coming under the purview of the India Boiler Regulation, bend radius shall be as per IBR.
b)
If permitted in piping material specifications, welded miter bends, with a maximum angle of 30 degree per segment, may be used in utility piping systems other than steam lines. Welded miter bends if approved by owner shall strictly conform to ASMEB 31.3.
4.0
MATERIAL
4.1
PIPING MATERIAL SPECIFICATIONS Various requirements for piping materials shall be prepared by the Contractor, which will give specification for pipes, valves, flanges, fittings, bolting, gaskets and other material requirements for various classes of fluid, temperature and pressure services and shall include datasheets for applicable classifications based on process & mechanical design conditions. The same shall be submitted for COMPANY's approval.
4.2
VALVES a) Type and size of valve shall be as per approved P&IDs and PMS prepared by the Contractor. b) If control valve sizes are not specified in the P&ID, the end connection shall be based on sizing calculations of control valve manufacture. c) For instrumentation, the primary block valves only are usually shown on P&IDs. d) Vent valves at high points and drains at low points, shall be provided and shown on the piping isometrics. VALVE MATERAIL SPECIFICATIONS SHALL BE PREPARED AND SUBMITTED FOR COMPANY’S APPROVAL
4.3
STRAINERS
Onshore Engineering Services New Delhi PROJ: Assam Renewal Project Job No.: OESG-AA-07-001
PIPING DESIGN BASIS
DOCUMENT NO.: OESG/ARP/DB/0006
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Y- Strainers shall be provided up to 1-½" size and 'T' strainers for 2" and above unless otherwise specified. 4.4 NACE PIPING (wherever required/specified) Material of construction of various piping items shall be suitable to withstand Sulphide stress cracking (SSC) and Hydrogen Induced Cracking (HIC) due to the presence of H2S in the fluid. The material should also be suitable to prevent the equipment from corrosion due to the presence of CO2 . The MOC of piping material & fabrication of piping shall meet the requirements of NACE-MR-01-75.
5.0
GENERAL
5.1
ELECTRICAL TRACING a) Electrical heat tracing shall be provided for pipe lines handling fluids and connected instruments for temperature maintenance or to prevent any congealing of fluids handled for those services as specified and shown on P&IDs. All instruments coming on these lines shall also be electrically heat traced. b) The electrical heat tracing for instruments/valves/flanges shall be done in such a manner that the servicing of instruments/opening of valves / servicing of flanges is possible without disconnecting of wiring and with ease.
5.2
NDT REQUIREMENTS Depending on the severity of application, extent of NDT shall be decided. As a rule, all hydrogen, oxygen, NACE, alloy steel and any other lethal and high-pressure service shall have 100% radiography on weld joints. Castings used in these services shall have 50% radiography.
5.3
STRESS ANALYSIS Piping arrangement shall provide for flexibility of lines to take care of the thermal expansion, contraction and equipment settlement. Expansion computation shall be made on the basis of a base temperature of 21.1 oC and shall cover +ve or -ve design temperature(s) as indicated in start-up and shut down conditions. Flexibility analysis shall meet the requirements of code ASME B 31.3 (latest edition) and shall consider stress intensification factor. Hydrocarbon lines, which shall be subjected to steam out conditions, shall be designed and analyzed at low pressure steam design temp or design
Onshore Engineering Services New Delhi PROJ: Assam Renewal Project Job No.: OESG-AA-07-001
PIPING DESIGN BASIS
DOCUMENT NO.: OESG/ARP/DB/0006
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temperature of line whichever is more. Lines having negative design temperature shall be analyzed for both conditions separately. Flexibility analysis of lines shall be carried out using simplified methods or a comprehensive computer program. Pipe stress analysis to be carried out inside the plant /terminal area using latest Caesar/ suitable software and a report generated of the same showing various load cases. This shall be put up for review and approval.
5.4
DYNAMIC ANALYSIS Dynamic analysis shall be performed by the contractor for all two phase lines in the plant in order to ensure that the lines are provided with proper supports and no vibration is there during normal operation as well as during start-up or any upset conditions. A list of such lines shall be prepared by the Contractor and shall be submitted for approval by COMPANY.
5.5
Deleted
5.6
Deleted
5.7
PIPING LAYOUT The following general piping requirements shall be complied by the Contractor.
5.7.1
Flare header should be free draining toward flare K.O. drum. The elevation of flare header shall be minimum 9.00 ( as per MoEF guideline ) meters above the FFL/FGL/Top of the road through its run up to Flare K.O. drum. However, in case of flare line crossing the public road, government / statutory requirements shall be complied by the Contractor.
5.7.2
All discharges into flare header should be designed to eliminate any liquid pockets.
5.7.3
Down stream of all PSV’s should be free draining towards flare header/connected vessel.
5.7.4
Contractor’s scope shall include provision of access platforms, walkways etc. for access to all valves/valve manifolds / instruments etc.
5.7.5
Only horizontal loop shall be provided as per requirement to accommodate thermal expansion. The desired loop shall be ensured through out including flat loop. The flare header shall be supported on shoes of height ranging from 100mm to 300mm. Proper thermal analysis temperature shall be established including possibility of temperature gradient along the line before providing expansion loops. Efforts shall be made to minimize the loops. The flare piping to off side shall be Onshore Engineering Services New Delhi PROJ: Assam Renewal Project Job No.: OESG-AA-07-001
PIPING DESIGN BASIS
DOCUMENT NO.: OESG/ARP/DB/0006
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provided with guide supports on all around the pipe to prevent it falling from the flare trestle. 5.8
EQUIPMENT LAYOUT The layout of equipment shall be based on following principles:•
•
•
•
To locate all equipments indentified on equipment list. To comply with codes and standards, regulations, P&ID’s, Project specifications and sound engineering/ industrial practices. To maximize safety of personnel, equipment and facilities. To ensure operability & maintainability of equipment with provision of adequate clearances all around in horizontal and vertical direction.
•
To provide means of escape and access for f ire fighting.
•
To minimize shutdown duration.
•
To comply with requirements of area classification.
•
To comply with all requirements of OISD & other statutory agencies
Onshore Engineering Services New Delhi PROJ: Assam Renewal Project Job No.: OESG-AA-07-001
PIPING DESIGN BASIS
DOCUMENT NO.: OESG/ARP/DB/0006
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