POST WELD HEADTREATMENT SERVICE
Electrical Heat Treatment Service

On site pre-heating hydrogen de-gasification and post weld heat treatment of pipe work, welded fabrication, and pressure vessel. Flexible electrical resistance heating elements are manufactured in a range of sizes to suit a wide range of applications and are connected to either low Voltage (65 Volt) or High Voltage (240 Volt) power sources.

Temperature control via pre-programmable microprocessor based modules and temperature measurement bypre-calibrated temperature recorders. All temperature neasuring equipment is calibrated in accordance with national standards

PREHEATING
Is the application of heat to the base metal prior to welding or cutting operations. It does not change the properties of the steel, but ut advisable under certain conditions to drive off moisture and helps to ensure even expansion to eleminate undesirable stresses. Concurrent heating during welding (also referred to as preheating) retards the cooling thus preventing the formulation of an under bead crack.

STRESS RELIEVING (POST WELD HEAT TREATMENT)
Is the heating of steel to relatively high temperature and maintaining that temperature for specific period of time. The purpose is to reduce internal stresses, caused by welding, quench hardening or by cold working. It also has an advantageous effect on the elasticity, ductility, and strength of themetal. This process involves heating the steel to a temperature below the material transformation point.

ANNEALING
Is essentially the softening of metal to make it more malleable. The process involves a controlled heating, and slow cooling which induces softness and ductility. Additionally, the process removes gasses, relieves stresses, and enhances the mechanical properties in alloyed steels.
This is generally performed at temperatures above the materials’ re-crystallization point.

NORMALIZING
Is much like annealing, but the cooling process is much faster. This results in increased strength but less ductility in the metal. It also produces a higher yield strength with greates tensile strength, and most instances, a higher impact resistance. This process involves heating the steel to just above the upper critical limit.