API RP 934-C:2008 pdf download
API RP 934-C:2008 pdf download.Materials and Fabrication of 11/4Cr-1/2Mo Steel Heavy Wall Pressure Vessels for High-pressure Hydrogen Service Operating at or Below 825 °F (441。C).
5.1.3 Nozzles should be manufactured from forgings. For thicker nozzles, 2 11.Cr-1 Mo may be used to ensure that toughness requirements are met. When us4ng 2 1)4Cr-1 Mo, appropriate weld procedures with higher preheat, PWHT temperatures, etc. should be used. Welding procedures should be approved by the purchaser,
5.2 Steel Making Practice
In addition to the steel making practice outlined in the applicable specifications, the steels should be vacuum degassed.
5.3 Chemical Composition Limits
For 1 1i4Cr-1/2Mo steel, all plate and forging materials should be made to fine grain practice and should meet the following additional chemical requirements by heat analysis.
X-bar (lop + 5Sb + 45n + AflflOO S 15 ppm
where
P, Sb. Sn, and As are in ppm.
Additionally
— CisO.lSwt%max;
— PisO.OO7wt%max;
— .sesO.OOlwt%max;
— CuisO.2Owt%max;and
— Niis0.3Owt%max.
5.4 Heat Treatment
All product forms should be normalized and tempered (N&T) or quenched and tempered (O&T) to meet the required mechanical properties. For equal to or greater than 2 Wt (50 mm) thickness, Q&T is typically required to meet the properties specified in this recommended practice.
5.5 Mechanical Properties
5.5.1 Location ef Test Specim.ns
Test specinens for establishing the tensile and impact properties should be removed from the following locations:
a) Plate—from each plate transverse to the rolling directrnn In accordance with ASME SA-20 at the standard test locations and at the 1izT location. When permitted by the applicable product specification, coupons for all tests should be obtained from the 1/2T location only. If required. 112T specimens should be used for hot tensile test
b) Forging—from each heat transverse to the major working direction in accordance with ASME SA-182 or ASME SA-336, and test specimens should be taken at 112T of the prolongation or of a separate test block, A separate test block, if used, should be made from the same heat and should receive substantially the same reduction and type of hot working as the production forgings that it represents and should be of the same nominal thickness as the production forg’ings. The separate test forging should be heat treated ii the same fumace charge and under the same conditions as the production forgings,
7.4.1.1 The chemical cxwnposition of the weld deposit representing each different welding procedure should be checked by either laboratory chemical analyses or by using a portable analyzer of suitable accuracy and precision.
7.4.1.2 The chromium and molybdenum content of the weld deposits should be within the ranges specified in ASME BPVC. Section II. Part C for the specified electrodes.
7.4.2 Hardness of Weld Deposit and Adjacent Base Metal
7.4.2.1 After final PWHT (see 7.6) hardness determinations should be made for each pressure-retaining weld (including each nozzle arid attachment welds) using a portable hardness tester,
7.4.12 Each hardness test result should be the average of three impressions at each test location. The test locations should include weld metal and base metals adjacent to the fusion line on both sides. AN individual hardness values should be reported.
7.4.2.3 Hardness values should riot exceed 225 HBW.
7.4.2.4 Hardness tests should be performed on each 10 if (3 m) length of weld, or fraction thereof. This testing
should be performed on the side exposed to the process environment when accessible.
7.4.3 Weld Impact Tests
Production test plates subjected to the minmium and maximum PWHT should be tested and should meet the requirements of 55.3.
7.5 Weld Overlay or Integral Clad
Both austenitic stainless steel and ferrihc stainless steel may be used for integral cladding of steel. However. austenitic stainless steel is typically used for the corrosion resistant weld overlay, which also applies to clad restoration welding. The following special requirements should apply for the austenitic stainless steel overlay.
7.5.1 Material Requirements
The ferrite content of austenitic stainless steel weld overlay should be between 3 FN and 10 FN, as deteimlied in accordance with WRC Bulletin 342. prior to any PWHT.
7.5.2 Disbonding Tests
Experience indicates that the risk of disbonding is low at the thicknesses and hydrogen charging levels at which 1 1/4Cr-1/2Mo is used. If testing is considered, API 934-A can be used as a resource document. The purchaser should define testing requirements and acceptance criteria.
