Skip to main content

PWHT EXEMPTION REQUIREMENTS IN ASME CODES

PWHT EXEMPTION REQUIREMENTS IN ASME CODES


In order to guess the technical background on PWHT exemption, PWHT exemption requirements in several ASME codes are reviewed. ASME codes suggested that PWHT is not mandatory when the nominal material thickness is not more than the thickness in Table 1.  

There was some variation between codes as shown in Table 1, and the reason for this has been not known. There are the general trends that the permitted thicknesses without PWHT is increased with increasing preheat temperature together with reductions in maximum carbon level, and the permitted thickness is decreased with increasing alloy content of steels. Most manufacturers are trying to avoid PWHT based on the Table 1 because there is an economic incentive to avoid PWHT. 




REFERENCES 

[1] Pingsha Dong and J.K.Hong, "Residual stress relief in post-weld heat treatment", 2008 ASME Pressure Vessels and Piping Conference, PVP2008-61210. 

[2] ASME Section III, NX, "Rules for Construction of Nuclear Facility Components", ASME, 2010. 

[3] ASME B31.1, "Power Piping", ASME, 2010. 

[4] ASME B31.3, "Process Piping", ASME, 2010. 

[5] Goldak J. et al., "New finite element model for welding heat sources", Metallurgical transactions B, Process metallurgy, 15B(2), 1984.

Comments

Post a Comment

Popular posts from this blog

MILL TEST CERTIFICATE is...?

  A Mill Test Certificate (MTC), or Mill Test Report (MTR), is issued by a manufacturer to certify the chemical and mechanical features of a product and its compliance to the applicable norms and technical specifications. Typically, Mill Test Certificates conform to the EN 10204 standard and are related to steel products. MILL TEST CERTIFICATE A mill test certificate to EN 10204 shows, generally, the following information: Type of certificate and standard (example EN 10204 3.1 or EN 10204 3.2) Manufacturer name Product name and dimensions Quantity covered by the certificate (example: tons, with heat numbers) Heat numbers and batch number (physically shown on the product as well) Final test result Dimensional measurements, to check compliance with allowed tolerances (example, for steel pipes: diameter, wall thickness, length, straightness) Material grade and applicable specification, including results of chemical and mechanical tests Results of additional tests, like hydrostatic, ultras
Post a Comment
Read more

Storage Tank API 650 - Summary

Shop Fabrication Inspection 1         Material Receiving Inspection Report Ø       Check visual (free of lamination & damage). Ø       Check certificate (keaslian, Heat No & Plate No). Ø       Check dimensional (Length, Thickness, Width & Diameter). 2         Marking Ø       Check dimensional marking. Ø       Check transfer heat no. 3         After Cutting Ø       Check dimensional. Ø       Check traceability (Heat No & Plate No). Ø       Check Stamp Marking. 4         Rolling Ø       Check visual (free of damage). Ø       Check edge preparation. Ø       Check Rolling radius. 5         Painting Ø       Check material painting (batch no, self life, brand). Ø       Check Ambient Condition (surface & whether). Ø       Check DFT. Field Erection Inspection 6         Dimensional Inspection 1         Peaking banding Peaking measured using a horizontal sweep board 36 inch (900 mm) long. Tolerance of peaking shall not exceed
Post a Comment
Read more