API 520

Part 1-Sizing & SelectionPart 2-Installation

Scope Scope

• Equipment MAWP > 15 psig(103 kPag)• Unfired pressure vessel• Sizing procedures and methods

• Overpressure/Structural failureAt h i d l t • Atmospheric and low pressure storage tanks

• Fired vessel – Section 1,ASME Boiler and V l d & ASME B31 1pressure Vessel code & ASME B31.1

Press re Relief De icePressure Relief Device• Re closing Type

a A Relief Valvea. A Relief Valveb. Safety Valvec. Safety Relief Valved. Conventional Pressure Relief

Valvee. Balanced Pressure Relief Valvef. Pilot Operated Pressure Relief

Valve

• Re closing Typea. Rupture Discb Pin-actuated Deviceb. Pin-actuated Device

Dimensional Characteristics of Pressure Relief Device

• Actual discharge area• Effective discharge area• Bore area• Bore area• Huddling chamber• Inlet size

i• Outlet size• Curtain area• Lift• Minimum net flow area

Operational Characteristicsp• coefficient of discharge:

a. Effective coefficient of dischargea. Effective coefficient of dischargeb. Rated coefficient of discharge

System Pressures and Temperatures

• Maximum operating pressure• Maximum operating pressure• Maximum allowable working pressure

(MAWP)/design pressure• AccumulationAccumulation• Overpressure• rated relieving capacity

Device PressureDevice Pressure• Set Pressure• The cold differential test pressure (CDTP)• The burst pressure• The burst pressure• The marked burst pressure or rated burst pressure• The specified burst pressure• Burst-pressure tolerance• Lot of rupture disks• The manufacturing range• Back pressure• Built-up back pressure• Built-up back pressure• Superimposed back pressure• Blowdown• Opening pressure• Closing Pressure• Simmer• operating ratio• Leak-test pressureLeak test pressure• relieving conditions• specified disk temperature of a rupture disc

Spring-Loaded Pressure Relief Valves(Gas/Vapor Service)(Gas/Vapor Service)• Conventional Pressure Relief Valves

safety valves/ relief valve/ safety relief valves

Conventional Pressure Relief Valve with a Single Adjusting Ring for Blowdown ControlSingle Adjusting Ring for Blowdown Control

Conventional Pressure Relief Valve with Th d d C tiThreaded Connections

Relationship Between Lift of Disk ina Pressure Relief Valve and Vessel Pressurea Pressure Relief Valve and Vessel Pressure

Spring-Loaded Pressure Relief Valves( Li id S i )( Liquid Service )

Balanced Pressure Relief Valves

Pilot-Operated Pressure Relief V lValves

• Partsa. Main Valveb. A Floating Unbalanced Piston

Assemblyc. An External Pilot (pop/modulating)

• Typesa The flowing Typea. The flowing Typeb. The Non flowing Type

Pop-Action Pilot-Operated Valve (Flowing-Type)Pop Action Pilot Operated Valve (Flowing Type)

Pop-Action Pilot-Operated Valve (Non flowing-Type)

Modulating Pilot-Operated Valve (Flowing-Type)

Pilot-Operated Relief Valve with a Nonflowing M d l ti Pil t V lModulating Pilot Valve

RUPTURE DISK DEVICES (Rupture Disc)

• Single, Multiple, and Fire Applicationsg• Rupture Disk Device at the Inlet of a

Pressure Relief Valve• Rupture Disk Device at the Outlet of a

Pressure Relief Valve• Highly Corrosive/Highly Viscous

• Typesa. Forward-acting, tension loaded.b Reverse-acting compression loadedb. Reverse acting, compression loaded.c. Graphite, shear loaded.

Forward-Acting Scored Rupture Disk

Forward-Acting Composite Rupture Diskg p p

Reverse-Acting Rupture Disk with Knife Blades

Reverse-Acting Scored Rupture Diskg S p

Graphite Rupture DiskGraphite Rupture Disk

Buckling Pin Valveg

Manufacturing Ranges and Corresponding Burst P M kiPressure Marking

• DETERMINATION OF RELIEFDETERMINATION OF RELIEFREQUIREMENTS(API 521)

• API EFFECTIVE AREA AND EFFECTIVE COEFFICIENT OF DISCHARGE(API 526)COEFFICIENT OF DISCHARGE(API 526)

Part 2 InstallationPart 2- Installation• Inlet Piping to Pressure-Relief Devices

a. Flow and Stress Considerationsa. o a d S ess Co s de a o sb. Vibration Considerationsc. Pressure Loss at the Pressure-Relief Valve Inletd Size and Length of Inlet Piping to Pressured. Size and Length of Inlet Piping to Pressure-

Relief Valves

REFERENCED PUBLICATIONS• API RP 520 Sizing, Selection, and Installation of Pressure-

Relieving Devices in Refineries, Part II, “Installation”• API Std 526 Flanged Steel Pressure Relief Valves• API Std 510 Pressure Vessel Inspection Code—

Maintenance Inspection, Rating, Repair, and Alteration• API RP 521 Guide for Pressure-Relieving and

D i S tDepressuring Systems• API Std 527 Seat Tightness of Pressure Relief Valves• API RP 576 Inspection of Pressure-Relieving Devices

API Std 2000 V ti At h i d L P • API Std 2000 Venting Atmospheric and Low-Pressure Storage Tanks (Nonrefrigerated and Refrigerated).

• ASME Boiler and Pressure Vessel Code, Section I, “Power Boilers ”1998Power Boilers, 1998

• Boiler and Pressure Vessel Code, Section VIII, “Pressure Vessels,” Division 1, 1998

• B31.1 Power Piping, 1995, latest addendap g, ,• B31.3 Process Piping, 1996, latest addenda