The Need for Pre-Weld Heat Treatment

Fumanite’s state of the art technology controls the heat up and in so doing;

  • Reduces the levels of thermal stress.
  • Provides compensation for high heat losses.
  • Minimizes the rate of weld hardening.
  • Reduced porosity in the weld.
  • Reduced hydrogen cracking.
  • Improved micro structure of heat affected zone (HAZ).











The need for controlled post weld heat treatment (PWHT)

  • Relaxes residual stress
  • Relaxes thermal stress
  • Tempers the metal
  • Removes diffusible hydrogen
  • Improves metallurgical structure
  • Enhances strength and life of the material

The Benefits of Weld Preheating and Reducing Thermal Stress


  • Thermal Stresses Occur as Molten Weld Pools Cool
  • Cracking Can Occur Both During and After Welding
  • Colder Parent Metal Resists the Inevitable Contraction of the Weld Metal


  • Preheating reduces the temperature difference between the Weld Metal and the Parent Metal and Minimizes Potential Cracking

Pre Weld Heat Treating and High heat Loss


  • Heavy Wall Materials and Aluminum Alloys with higher thermal conductivity can act as a heat sink, drawing heat away from a weld and cooling at an accelerated rate.


  • Preheat Heat treatment will reduce the cooling rate of the deposited weld material and allow a proper fusion with the parent metal

Pre Weld Heat Treatment will Reduce Weld Porosity


  • If moisture is present at a welded joint, the high heat of the welding arc will break the water down into its elements, hydrogen and oxygen. The hydrogen by-product easily dissolves into the weld metal and causes weld porosity during weld solidification.


  • Performing a pre weld heat treat drives away moisture from the welded joint.

Pre Weld Heat Treatment will Reduce Weld Hardening


  • During and after completing of the welding process, both the weld pool and the Heat Affected Zone (HAZ) can harden and crack when cooling at a rapid pace


  • By preheating the weld and the Heat Affected Zone (HAZ) the rate of cooling can be controlled and reduced thereby eliminating problems associated with weld hardening

Pre Weld Heat Treating Prevent Hydrogen Cracking


  • Electrode Coatings and Fluxes can often introduce moisture directly to the arc and weld pool. The increase in moistures increases the possibility of weld or Heat Affected Zone (HAZ) cracking.


  • Preheating slows down the weld cooling rate which allows hydrogen to escape

Pre Weld Heating Improves Material Microstructure


  • Low Alloy Steels containing elements such as chromium, nickel, molybdenum, and vanadium are susceptible to cracking in the Heat Affected Zone (HAZ)


  • Preheating improves the microstructure inside the HAZ by reducing the post weld cooling rate. The reduced cooling rate produces:
    • A more desirable and ductile microstructure to be formed
    • Minimizes Under Surface Cracking

Furmanite - Innovative since 1920

Leak Sealing process developed leak-sealing-developed_thumb 01/01/1920

Furmanite Leak-Sealing process is Developed The under pressure Leak Sealing process is developed by Eugene Clay Furman at the Newport …

First DIY Leak-Sealing Kit old-furmanite-leak-sealing-equipment 01/01/1924

First DIY Leak-Sealing Kit The first do-it-yourself Leak Sealing kits were developed and marketed by Clay Furman and while they …

Long Standing Relationships Sales-Brochure-1926_thumb 01/01/1926

Long Standing Relationships US customer reference list that includes individual war ships in the US Navy, US steel companies and …

1st Patent is filed in 1927 furmanite-patents1 01/01/1927

1st Patent is filed in 1927 The Furmanite patent for the leak sealing process filed in 1927 was the first …

Furmanite moves Overseas Liverpool-Exibition_thumb 06/01/1927

Furmanite moves Overseas First overseas agents appointed to market the leak Sealing kits including in the United Kingdom and Euro…

Costs of a steam leak Sales-Brochure-1926-pg-8_thumb 06/01/1928

Price List from 1926 Table detailing costs of allowing a steam leak based on $4 per ton for “Long coal”. …

Furmanite is thinking global furmanite-the-skys-the-limit_thumb 01/01/1929

Furmanite is thinking global A brief history of the United Kingdom Company written by A W Forsyth (OBE) in September 1973 …

Technology Development leak-sealing-diagram 11/22/1934

Technology Development Furmanite Expands Engineering on Leak Sealing Technology. Photographs taken from a 1934 sales brochure together with schematics of …

Growing Furmanite purchase-letter_thumb 05/01/1960

Growing Furmanite Letter from the Chairman of Furmanite Engineering based in Birkenhead, England to his lawyer requesting information on a …

New Direction New-Technology_thumb 01/01/1966

New Direction Alan Forsyth, acting as a consultant to Furmanite Engineering (1929) advised the Board to move from selling low …

Never compromise on the high quality Company-History-July-1979_thumb 07/01/1979

Never to compromise on the high quality A brief history of the United Kingdom Furmanite organisation written by Joyce Hainsworth, the …

Best in the business were called NASA---Discovery-Team_thumb 09/01/1988

Best in the business were called Furmanite successfully seals nitrous oxide leakage on the Space Shuttle “Discovery” pre launch September …

Start of Modern Furmanite company-overview 11/22/1991

Start of Modern Furmanite The common shares of Furmanite were acquired by Kaneb Inc on 24th January 1991. Furmanite remains …

Acquisition-GSG Division Acquisition-GSG-Division_thumb 01/13/2006

Acquisition of Flow-Serve GSG Division Furmanite as part of Xanser Corporation acquired the General Services Group (GSG) of Flow-Serve corporation …

Corporate Name Change Corporate-Name-Change_thumb 01/13/2007

Corporate Name Change Xanser Corporation (NYSE:XNR) changed the company’s name to Furmanite Corporation, and the company’s shares were traded on …

Acquisition of SLM Acquisition-of-SLM_thumb 04/13/2011

Furmanite Corporation Acquires Self Leveling Machining Technology Furmanite expanded  its global on-site machining capabilities through the acquisition of Self Leveling …


Contact Us

  • Note: Forms may be submitted only once per webpage session.
  • This field is for validation purposes and should be left unchanged.