Pipi Pi ping ng Cl Clas asse ses s - ob obje ject ctiv ives es • 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 Class A 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 resistanc resistance e
Every standard component has a unique identifying number, which describes requirements up to delivery (ordering, design, manufacture, inspection & certification)
A Piping Class A 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 resistanc resistance e
Every standard component has a unique identifying number, which describes requirements up to delivery (ordering, design, manufacture, inspection & certification)
Design Codes External Standards: • ASME Code for Pressure Piping, B31 – – – – –
ASME B31.1 ASME B31.3 ASME B31.4 ASME B31.8 ASME B31.9
• CEN • Local Codes
Power Piping Process Piping Liquid Transportation Piping Gas Transportation Piping Plumbing and Sanitation Piping
European Piping Code Country dependent
• ASME B31.3 Chemical Plant and Petroleum Refinery Piping This refers to other ASME/ANSI standards » AS ASME ME/A /ANS NSII B16 B16.5 .5 (& B1 B16. 6.47 47))
-Pip -P ipe e Fla Flang nges es (& fl flan ange ges s abo above ve 24 24”) ”)
Design Codes (cont.) • Shell Standards – DEP 31.38.01. 31.38.01.11-Gen 11-Gen “Piping – general requirements” 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 Equipment Standards and Code Code system 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 Piping Material
Piping Class
Medium
Service/remarks
Carbon Steel
1410
Hydrocarbons, Water, “Sweet” Glycol, Air, Diesel
Carbon Steel
1440
HC’s, Glycol, Seal Oil, “Sour”
316L
3410
Glycol, Hyd. oil, Chemicals, Firefighting foam
(60°C max if chlorides)
Duplex
3831/2 3833/4
HC’s
1/2 corrosive 3/4 corrosive/sour
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: – G = 152.4 mm
400 Barg
• 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
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
Sizing of Valve Actuator • Valve requirements: – Establish valve torque plus safety margin » » » »
Temperature Medium Contamination Condition / frequency of operation
• Manual Operator – Force – Lever Length – Hand-wheel diameter – Hand-wheel turns
<350N
• Power operator – Check complete output curve
Check Valve applications • Prevent reverse rotation of pumps (seal/driver damage) • Prevent downstream lines/reservoirs from draining backwards Non Critical
Reduced pressure loss Reduced operating cost
Parallel Pump system Compressor recycle
Pump Discharge
Swing
Critical
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 and Overpressure Protection
Pressure drop across valves
