Enhancing Corrosion Resistance and Material Strength Through Specialized Finishing Processes

Heat treatment of pipe fittings is a critical process in industrial manufacturing that involves controlled heating and cooling cycles to enhance mechanical strength, toughness, and corrosion resistance. Depending on the material—such as stainless steel, carbon steel, or high-alloy metals—various heat treatment methods like annealing, normalizing, or quenching are applied to meet project-specific performance standards in industries like oil & gas, power plants, and chemical processing.

Here are some common heat treatment processes for different types of pipe fittings:

• Annealing
• Normalizing
• Quenching and Tempering

• Stress relieving is a heat treatment process used to reduce residual stresses in pipe fittings caused by welding or machining.
• The fittings are heated to a temperature below the material's critical transformation temperature and held for a specific time.
• The fittings are then slowly cooled down to room temperature to relieve internal stresses and minimize the risk of cracking or distortion.

Solution annealing is a heat treatment process commonly used for materials such as stainless steel and some non-ferrous alloys. It aims to dissolve and eliminate any unwanted precipitates or phases formed during previous manufacturing processes, restore the material's microstructure, and improve its mechanical properties.

Solution Annealing + Stabilized Heat Treatment done for SS material.

Stabilization Treatment

Stabilization Treatment refers to a heat treatment method for Austenitic Stainless steel containing Titanium or Niobium to improve the resistance to inter granular corrosion. Such as 321H, 347H and other materials.

All types of SS321, SS347 or SS348 fittings shall be in stabilized heat treated condition. Stabilizing heat treatment shall be carried out subsequent to normal solution annealing. Soaking temperature and holding time for stabilizing heat treatment shall be 9000C and 4 hours respectively.

Stabilization treatment for pipe fittings typically involves measures to enhance their stability, strength, and longevity in the intended application. Here are some common stabilization treatments for pipe fittings:

Here are some common stabilization treatments for pipe fittings:

• Corrosion Protection
• Surface Treatment
• Heat Treatment
• Thread Locking
• Pressure Testing
• Quality Control

Pickling: Generally, the workpiece is immersed in an aqueous solution such as sulfuric acid to remove films such as oxides on the metal surface. It is the pretreatment or intermediate treatment of electroplating, enamel, rolling and other processes.

Each SS materials fitting shall be undergo pickling and passivation as per ASTM A380

The pickling process typically involves the following steps:

• Immersion
• Degreasing
• Neutralization

Passivation: If the corrosion product generated by the metal due to the action of the medium has a dense structure, a thin film (often invisible) is formed and tightly covered on the surface of the metal, which changes the surface state of the metal and makes the metal The electrode potential jumps greatly to the positive direction, and becomes a passive state of corrosion resistance.

The passivation process typically involves the following steps:

• Cleaning
• Passivating Agent
• Dwell Time
• Rinse