PWHT jobs involve preheating and postweld heat treatment (PWHT) of pipe welds and equipment according to company, quality and client standards. This typically requires reading documentation, monitoring preheat charts and operating equipment. PWHT is necessary to reduce residual stresses in welded components and can be time and cost intensive; some codes even mandate it for materials with thickness over certain limits. Qualifications PWHT (Pressure Weld Heat Treating) is a thermal process involving high-temperature heating followed by rapid cooling in liquid medium. PWHT improves mechanical properties in welded materials such as toughness and ductility while increasing resistance against cracking under dynamic load conditions, typically seen on carbon steels as well as …

続きを読む “Pwht Jobs”

PWHT (post-weld heat treatment) is an integral component of welding that reduces residual stresses and tempers the heat affected zone, as well as improving weld ductility to avoid cold cracking. PWHT involves heating a material to an exact temperature for an extended period, then gradually cooling it over time. It is an intricate process requiring specialist equipment and facilities. Annealing Heating method and the rate at which metal cools have an enormous influence on its final properties. Experienced experts know exactly how to balance these variables to transform ordinary metal into project-specific materials that meet all your specifications. Annealing softens material’s structure by increasing its ductility and decreasing hardness – …

続きを読む “PWHT – A Necessary Step in the Welding Process”

Prior to 2014, ASME B31.3 required carbon steel welds be post weld heat treated (PWHT). However, with recent amendments of this Code allowing exemptions when weld thickness exceeds certain limits, post weld heat treatment becomes optional in certain instances. This paper will analyze the arguments used to justify exemptions, showing many to be invalid or incomplete. Furthermore, an EPC contractor’s perspective will also be provided along with practical approaches that may help mitigate risks. PWHT Requirements PWHT of carbon steel can be an expensive and complex process, yet there has been growing interest in eliminating its requirement from fabrication standards for certain applications. This trend can particularly be found within …

続きを読む “Comparison of ASME B31 3 PWHT Requirements”

The B31.3 Code defines rules for piping systems used in oil refineries, chemical, paper & pulp, semiconductor manufacturing facilities, power generation stations and similar processing plants. This document specifies requirements for designing, fabricating, assembly erection examination inspection & testing of process piping. An EPRI report (Ref 1) has recommended that the PWHT temperature for 1-1/4 Cr materials should be reduced, and this report will support that change within B31.1 and B31.3 codes. 1. PWHT Temperature Range Different codes governing pressure vessels and piping vary considerably on various issues, including required PWHT temperatures. Most differences arise due to industry traditions rather than specific metallurgical or structural considerations; as a result, attaining …

続きを読む “B31.3 PWHT Table”

Post-weld heat treatment (PWHT), commonly referred to as stress relief, involves heating and cooling welds to alleviate residual stresses that could otherwise lead to cracking and fractured welds. PWHT involves specific rates, tolerances and times at temperature that Wisconsin Oven furnaces offer for maximum stress-relief. Annealing, normalizing and stress relieving are just some of its applications for PWHT treatments. Process Post weld heat treatment (PWHT), commonly referred to as stress relief heat treatment, tempers the metal and reduces residual stresses caused by welding, thus decreasing fatigue cracking rates and increasing resistance against brittle fracture. PWHT is an essential step in maintaining integrity for structures or equipment exposed to dynamic loads. …

続きを読む “A Qualified PWHT Company Is Essential For Your Project”

Since 2014’s edition of ASME B31.3, thick carbon steel pipe has been exempted from post weld heat treatment (PWHT) requirements with only multi-pass welding required and no preheat requirement necessary. There have been concerns raised that such exemptions may be unsafe. This paper, sponsored by EPRI and written by RRAC team members, is intended to support changes to minimum PWHT temperature requirements of B31.1 and B31.3 codes as well as similar changes elsewhere in codes. Minimum Preheat Temperature ASME B31.3’s minimum preheat temperature requirements differ significantly across codes and standards, possibly reflecting different service conditions addressed by each standard or code. Real concerns emerge when requirements of one code or …

続きを読む “ASME B31.3 Post Weld Heat Treatment Requirements For Carbon Steel Pipe”

This week marked the debut of the Professional Women’s Hockey League season and its rules will differ significantly from those seen in the National Hockey League (NHL). While teams in NHL receive two points for winning an overtime or shootout game, while in PWHL they only get credit if their victory came during regulation time. Jailbreak Goals Professional Women’s Hockey League (PWHL) fans have taken notice of a unique rule known as a jailbreak goal that allows a player serving a penalty to be released if her team scores a shorthanded goal during her penalty session. It adds a level of excitement and anticipation during games this season; Erin Brown …

続きを読む “The Shootout and Jailbreak Goal in PWHL Hockey”