Rakesh Kelekar

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sales@infinitythermotech.com

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Talawade, Pune-412114

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PWHT

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Stress Relief & Metallurgical Integrity for Welded Industrial Components

Welding is a critical fabrication process across heavy engineering, pressure equipment, pipelines, and structural manufacturing. However, welding also introduces high residual stresses, hardness variations, metallurgical imbalance, and reduced toughness in and around the weld zone. If left untreated, these issues can lead to cracking, distortion, brittle failure, corrosion susceptibility, and reduced service life.
 PWHT (Post Weld Heat Treatment) is an essential metallurgical process designed to restore material integrity, relieve stresses, and ensure long-term reliability of welded components.

AtInfinity Thermotech Solutions Private Limited, we provide precision-controlled PWHT / post weld heat treatment services in Pune for carbon steels, alloy steels, and pressure-retaining components. Our process-driven approach helps manufacturers meet code compliance, performance reliability, and safety requirements across critical industries.

PWHT Process at Infinity Thermotech

At Infinity Thermotech, PWHT is carried out with strict control over temperature uniformity, soak time, and heating/cooling rates, ensuring compliance with customer specifications and applicable codes.

Our PWHT process includes:

  • Controlled ramp-up and ramp-down heating cycles

  • Uniform temperature distribution across the welded zone

  • Precise soaking time based on material thickness

  • Metallurgically safe cooling rates to prevent re-hardening

We offer furnace-based PWHT as well as localized PWHT solutions for large or site-installed components, ensuring flexibility across fabrication scales.

The Science Behind Annealing & Solution Annealing

What Is Post Weld Heat Treatment (PWHT)?

Post Weld Heat Treatment is a controlled heating and cooling process applied to welded components after welding is completed. The component is heated to a specified temperature (below transformation temperature), held for a defined period, and then cooled at a controlled rate.

The primary objectives of PWHT are to:

  • Relieve residual stresses generated during welding

     

  • Reduce hardness in the heat-affected zone (HAZ)

     

  • Improve toughness and ductility

     

  • Restore metallurgical balance

     

  • Minimize risk of hydrogen-induced cracking

     

PWHT is often mandatory for pressure vessels, boilers, pipelines, and structural components as per ASME, ASTM, ISO, and other industry codes.

PWHT Process at Infinity Thermotech

At Infinity Thermotech, PWHT is carried out with strict control over temperature uniformity, soak time, and heating/cooling rates, ensuring compliance with customer specifications and applicable codes.

Our PWHT process includes:

  • Controlled ramp-up and ramp-down heating cycles

     

  • Uniform temperature distribution across the welded zone

     

  • Precise soaking time based on material thickness

     

  • Metallurgically safe cooling rates to prevent re-hardening

     

We offer furnace-based PWHT as well as localized PWHT solutions for large or site-installed components, ensuring flexibility across fabrication scales.

Applications of Post Weld Heat Treatment

PWHT is essential for welded components operating under pressure, thermal cycling, fatigue loading, or corrosive environments.

Typical Components

  • Pressure vessels and boilers
  • Storage tanks and reactors
  • Pipelines and piping systems
  • Structural steel fabrications
  • Heat exchangers
  • Heavy machinery frames
  • Welded shafts and housings

Industries Served

  • Oil & gas
  • Power generation & energy
  • Petrochemical & chemical processing
  • Heavy engineering & fabrication
  • Infrastructure & construction
  • Industrial machinery manufacturing

Key Benefits of Age Hardening Heat Treatment

High Strength Without Surface Hardening

Uniform strengthening throughout the component.

Excellent Dimensional Stability

Minimal distortion when correctly controlled.

Improved Fatigue Resistance

Ideal for cyclic load and high-stress applications.

Enhanced Corrosion Resistance

Especially important for stainless steel and aluminium alloys.

Optimized Strength-to-Weight Ratio

Critical for aerospace and automotive applications.

Age Hardening vs Other Heat Treatment Processes

Age hardening is fundamentally different from surface hardening processes. For components requiring deep surface hardness and wear resistance, Carburising Hardening & Tempering is more suitable.

Where high surface hardness with minimal distortion is required, Nitriding provides an effective alternative. For applications demanding combined wear resistance, fatigue strength, and corrosion protection, Nitrocarburising offers a balanced surface engineering solution.

Infinity Thermotech provides all these processes, allowing customers to select the most technically and economically appropriate heat treatment solution.

Why Choose Infinity Thermotech Solutions Private Limited?

  • Expertise in precipitation hardening of aluminium, stainless steel & nickel alloys
  • Precision-controlled furnaces and aging cycles
  • Consistent, repeatable metallurgical results
  • Support for prototype, batch, and production volumes
  • Technical consultation for material and process selection

Our goal is to deliver measurable improvements in strength, durability, and component performance.

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FAQs About Annealing & Solution Annealing

If you have any questions please ask us and we will answer you as quickly as possible Make a question now!
Q1.What is the difference between age hardening and surface hardening?

 Age hardening strengthens the entire component, while surface hardening affects only the outer layer.

 Yes. It is one of the most effective methods for strengthening aluminium alloys.

 When properly controlled, it maintains or enhances corrosion resistance, especially in PH stainless steels.

 Distortion is minimal when solution treatment and aging cycles are precisely controlled.