Version 1/2013
OVERVIEW
WHAT IS HEAT FUSION
The principle of heat fusion is to heat two surfaces to a designated temperature
and then fuse them together by application of force.
This pressure causes flow of the melted materials, which brings on mixing and
so the fusion.
When the PP-R material is heated, the molecular structure is transformed from
a crystalline state into an amorphous condition.
When fusion pressure is applied, the molecules from each PP-R part mix.
As the joint cools, the molecules return to their crystalline form, the original
shapes are changed, and the fitting and pipe have become one homogeneous
unit. The joint area becomes as strong as the pipe itself in both tensile and
pressure conditions.
The principal operations for the optimal fusion include:
Cleaning
The area of pipe that will come in contact with the fitting must be
cleaned.
Aligning
The fitting must be properly seated on the pipe for correct
alignment.
Heating
A rim of melted material must be formed both on the pipe and the
fitting.
Joining
The pipe and the fitting must be joined and the pipe has to be fully
seated within the fitting.
Holding
The molten joint must be kept immobile until it has cooled
adequately.
Inspection
Visually examine the entire circumference of the joint for
compliance with standards established by the company, customer,
industry, federal, state or local regulations.
