The pressure testing of Expansion Joints is essential in the industry.
It is important to distinguish between a Proof-Pressure Test and a Leak Detection Test. Expansion Joints need to be both, proof-pressure tested and tested for leak tightness, to ensure observance to regulations and safe and reliable operation.
A Proof-Pressure Test verifies if a component can withstand pressure above its intended operating pressure without permanent damage. It is a form of stress test to demonstrate the fitness of an Expansion Joint under the test pressure conditions.
The purpose of a leak detection test is obviously detecting and localizing leaks. In general, employed method of Leak Detection Test is Pneumatic at low pressure.
In this article, we will focus our attention in evaluating and reducing the risks of Pneumatic Proof-Pressure Testing in Expansion Joints.
The proof-pressure test shall always be hydrostatic, except where the hydrostatic pressure test is harmful or impractical or the Expansion Joint cannot safely be filled with water. In these instances, a pneumatic pressure test or other alternative tests may be performed.
When a hydrostatic pressure test cannot be performed, a pneumatic pressure test may be considered.
The stored energy of compressed gas is very high, so rupture of an Expansion Joint during a pneumatic pressure test can release much energy. Damage due to rupture can result from shock waves, flying projectile fragments from the ruptured unit, resulting in serious injuries and major equipment damage.