API 526 pdf download.Flanged Steel Pressure Relief Valves
2.1 GENERAL Pressure relief valves discussed in this standard shall be designed and manufactured in accordance with the applicable requirements of Section VIII of the ASME Boiler and Pres- sure Vessel Code for pressure relief devices. 2.2 DETERMINATION OF EFFECTIVE ORIFICE AREA The minimum required effective oriÞce area shall be deter- mined in accordance with API RP 520, Part I. 2.3 VALVE SELECTION For valves described in this standard, inlet and outlet ßange sizes and pressure-temperature ratings shall conform to the data in Tables 2 Ð 15 for spring-loaded valves and Tables 16 Ð 29 for pilot-operated valves. Inlet and outlet pressure limits are governed by the ßange pressure/tempera- ture limits or by the manufacturerÕs design limits, whichever is lower. 2.4 DIMENSIONS Center-to-face dimensions shall be in accordance with Tables 2 Ð 15 for spring-loaded valves and Tables 16 Ð 29 for pilot-operated valves, with tolerances of plus or minus 1 Ú 16 in. for valve inlet sizes up to and including 4 in., and plus or minus 1 Ú 8 in. for valve inlet sizes larger than 4 in. Flange facings and dimensions shall be in accordance with ASME/ANSI B16.5. For some valve designs, the inlet raised face height may substantially exceed the nominal dimension speciÞed in ASME/ANSI B16.5. Consult the manufacturer for exact dimensions. 2.5 LIFTING LEVERS Lifting levers shall be provided when required by the ASME Boiler and Pressure Vessel Code or when designated on the purchaserÕs speciÞcation sheet. As allowed by the Code for pilot-operated pressure relief valves, means in lieu of lifting levers may be speciÞed for connecting and applying adequate pressure to the pilot to ver- ify that the moving parts critical to proper operation are free to move. 2.6 SPECIAL CONSTRUCTION FEATURES Construction features beyond the scope of this standard shall be provided as agreed upon by the manufacturer and the purchaser and shall be designated on the drawings provided to the purchaser.
3.1 GENERAL Materials generally used for construction are covered in this section. For special corrosion problems and applications beyond the pressure-temperature limits of this standard, con- struction materials shall be those agreed upon by the manu- facturer and the purchaser. 3.2 SPRING-LOADED PRESSURE RELIEF VALVES The body, bonnet, and spring materials shall be in accor- dance with Tables 2 Ð 15 for the required temperature range. The body and bonnet may be of different materials but must meet the minimum pressure-temperature requirement. The body and bonnet materials shall be equivalent to or better than the following types and grades:Material for the pilot and internal parts of the valve shall be in accordance with the manufacturerÕs standards for the tem- perature and service or as indicated on the purchaserÕs speciÞ- cation sheet.
4 Inspection and Shop Tests
4.1 INSPECTION The purchaser reserves the right to witness the shop tests and inspect the valves in the manufacturerÕs plant to the extent speciÞed on the purchase order.4.2 SET PRESSURE TEST All pressure relief valves shall be adjusted to the speciÞed set pressure in accordance with the ASME Boiler and Pres- sure Vessel Code , the manufacturerÕs standard practice as published, or as designated by the purchaser. All set pressure adjustments shall be sealed. 4.3 SEAT LEAKAGE TEST All pressure relief valves shall be seat leakage tested in accordance with API Std 527, or as agreed upon by the manu- facturer and the purchaser.
5 Identification and Preparation for Shipment
5.1 IDENTIFICATION Each pressure relief valve shall have a corrosion-resistant nameplate permanently attached to the body or bonnet. This nameplate shall be stamped with the data speciÞed in Appen- dix B. Pilot-operated pressure relief valves shall have an addi- tional nameplate permanently attached to the pilot. The pilot nameplate shall be stamped with the manufacturerÕs name, pilot type, set pressure, and serial number. Each pressure relief valve shall be tagged with the pur- chaserÕs valve number or other identiÞcation as speciÞed on the purchase order. The data may be stamped on the name- plate or on a separate corrosion-resistant tag that is perma- nently attached to the valve. 5.2 PREPARATION FOR SHIPMENT Each pressure relief valve shall be prepared for shipment as follows: a. After test and inspection, all exterior surfaces, except ßange facings, shall be painted as agreed upon by the manu- facturer and the purchaser. Corrosion-resistant materials need not be painted. Flange facings shall be coated with a suitable corrosion inhibitor.