p221 piping classes

© 2000 Shell International Exploration and Production B.V. 20/06/2003 Title.ppt, page 1P221

Piping Classes - objectives

• Objectives of the session– Understand the principles behind the use of piping classes.– Awareness of the relevant codes and standards– To be able to apply the principles of piping classes in the

development of a design


A Piping ClassA set of standard piping components that under certain

service conditions, and within defined pressure/temperature limits, can be used together.

The “service conditions” are determined by the meduim(type of fluid) and it’s properties:

– Corrosivity– Sweet/Sour service– HIC resistance

Every standard component has a unique identifying number, which describes requirements up to delivery (ordering, design, manufacture, inspection & certification)


Design CodesExternal Standards:• ASME Code for Pressure Piping, B31

– ASME B31.1 Power Piping– ASME B31.3 Process Piping– ASME B31.4 Liquid Transportation Piping– ASME B31.8 Gas Transportation Piping– ASME B31.9 Plumbing and Sanitation Piping

• CEN European Piping Code• Local Codes Country dependent

• ASME B31.3 Chemical Plant and Petroleum Refinery PipingThis refers to other ASME/ANSI standards

» ASME/ANSI B16.5 (& B16.47) -Pipe Flanges (& flanges above 24”)» ASME/ANSI B16.34 -Valves


Design Codes (cont.)• Shell Standards

– DEP 31.38.01.11-Gen “Piping – general requirements”

– DEP 31.38.01.10-Gen “Basis of Design”– DEP 31.38.01.15-Gen “Piping Classes Exploration and Production”– DEP 31.38.01.12-Gen “Piping Classes Manufacturing”

MESC – Material and Equipment Standards and Code system


Scope of ASME B31.3

Includes• Materials, Design, Fabrication, Assembly, Testing, Inspection • Applicable fluid service

– Petroleum products; Chemicals; gas; steam; air and water; fluidised solids; refrigerants

Excludes• Non toxic, non-flammable fluids between 0-15psig• Tubes/Piping internal to heater enclosures• Pressure Vessels (HEX), pumps, compressors• Power (31.1), Liquid (31.4) & Gas (31.8) transportation piping/pipelines• Plumbing/sanitation (31.9)• Fire protection systems based on recognised standards


Other relevant Design Codes

Other relevant codes for flanges:– BS 1560 – equivalent to ASME B16.5 and B16.47– BS 3293 – follow same ratings as ASME

Pressure Vessel Codes: if not covered by above– ASME VIII Div 1 – BS 5500

Wellheads:– API 6A / 6B


Why do we have Piping Classes?

• Ensure the right material is selected for a particular service.

• Standardisation:

– Interchangeable– Economical– Reduces stock required– Reduces risk of maintenance error

• Reduces the number of different pipe specs. used in the facilities


Piping Class Identification


Pressure / Temperature

rating

ASME/ANSI B16.5 & B16.47


Piping Class Selection Guide• Fluid system characteristics

– Hydrocarbon single/multiphase, water,glycol etc.• Condition

– Sweet, sour, corrosive• Piping Class

– xxxx• Material selection

– Carbon steel, alloys, stainless steel, Duplex• Temperature range limits

– -20/120 deg C• Corrosion allowance

– 0-3 mm• Remarks

– Further limitations / special conditions


Some Common Piping Classes

1/2 corrosive3/4 corrosive/sour

HC’s3831/23833/4

Duplex

(60°C max if chlorides)

Glycol, Hyd. oil, Chemicals, Firefighting foam

3410316L

“Sour”HC’s, Glycol, Seal Oil, 1440Carbon Steel

“Sweet”Hydrocarbons, Water, Glycol, Air, Diesel

1410Carbon Steel

Service/remarksMediumPiping Class

Piping Material


Piping Class description


Piping Class information building


Flanges

4”- ASME 600 RF WN Flange, Bore 3.826”

ASME


Flange Loads


Gaskets


Example of Mechanical coupler assessment

• 6”Coupler– Rated Pressure: 400 Barg– G = 152.4 mm

• Loads– Internal Pressure: 360 Barg– External Bending moment: 15 kNm– Exterval Torsional moment: 10 kNm– External force: 5 kNm (in compression)

• Assessment:– Effective Moment: Me = [15 + √{152+102}]= 16.5 kNm– Equivalent pressure: Pe = 1.273 * [4 * Me/G+ 0]/G2 = 1.273 * ( 4*

16500/0.152.4)/(.15242) = 23.5 Barg– Peq+Pint: 360+23.5 = 383.5 Barg

– 383.5 Barg < 400 Barg: O.K.


Valves

Common Causes of failure:• Incorrect selection of valve type and/or material• Poor quality fabrication and/or construction of valve• Lack of inspection before installation• Inadequate cleaning of line before installation• Incorrect installation• Incorrect operation• Poor maintenance• Fouling, polymerisation and solid particles


Valve Selection considerations

• Service Requirements• Reliability• Availability• Operability and Maintainability

• Size and Weight• Cost


Valve type Selection Process• Info required (from Piping Class):

– Pressure & Temperature (operating and design)– System characteristics (medium and phase)– Condition (erosion/corrosion/toxic)

• Info required (from Process Engineer)– Valve Service:

» open/close; throttling; regulating/control; isolating– Capacity– Turndown capability– Safety requirements:

» Fire safe» Environmental limitations (leak paths etc.)» Min/max time constraints to open/close» Reliability» Fail-safe position


Classification of Valves


Block Valve characteristics comparison


Ball Valves vs Gate Valves


Ball Valves Advantages/disadvatanges


• Valve requirements:– Establish valve torque plus safety margin

» Temperature» Medium» Contamination» Condition / frequency of operation

• Manual Operator– Force <350N– Lever Length <twice valve length

<1m– Hand-wheel diameter <0.8m– Hand-wheel turns <100

• Power operator– Check complete output curve

Sizing of Valve Actuator


Check Valve applications

• Prevent reverse rotation of pumps (seal/driver damage)• Prevent downstream lines/reservoirs from draining

backwards

Non Critical CriticalReduced pressure lossReduced operating cost

Pump Discharge Parallel Pump systemCompressor recycle

Swing Dual Plate Non-Slam


Top Tips for Valve specification/installation

• Use Standard valve types (from Piping Class & MESC)• Seek advice from a valve specialist for non-standard

valves• Buy valves from approved (pre-qualified) Vendors

(ISO 9000 certificate)• If fluid temperature >180°C, use metal-to metal seals• Inspect valve (particularly intake) on delivery to site• Clean and inspect lines prior to installation• Make sure you install it the right way!


Top Tips for creating PEFs

DO think about/show:• Design Pressures• What type of equipment you’ll

employ• Process and Emergency

Shutdown• Isolation, Relief and Blowdown• Piping Sizing / Classes

– Spec breaks– Types/locations of Valves

Don’t worry too much about:• Being right !• Control issues• Primary safeguarding


The End


Spec Breaks andOverpressure Protection


Pressure drop across valves

p221 piping classes

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