Hydrotest: what is a hydrotest and how is it performed?

The gas and petrochemical industries require rigorous industrial controls and inspections to ensure the highest possible level of safety in their facilities. For this purpose, all manner of tests and trials are carried out, the most common being destructive and non-destructive tests.

What is a Hydrotest?

The Hydrotest or Hydrostatic Test is classified as a non-destructive test because the main objective is not to check the resistance, but rather the tightness of the parts.

The hyrdrotest is the most common test for pressure testing of pipes and vessels. It requires that the vessels (pipes, plumbing, gas cylinders, boilers and fuel tanks) or piping system be filled with water or any other liquid that can be stained to visually detect leaks. They are subjected to much more demanding conditions than will be encountered during operation in order to verify that the internal pressure remains constant.

Thus it helps maintain safety and durability standards.

What are hydrostatic tests for?

Hydrostatic testing is used to certify the homogeneity of the products, as it reveals previously undetected material defects.

The 2014/68/EU Pressure Equipment Directive mandates this test on any newly manufactured equipment or piping lines if they are to be installed in the field.

For example, some of the most common objects that undergo this type of testing are fire extinguishers, to ensure that the fire repellent material has not deteriorated or lost efficacy.

At ULMA Forja we perform hydrotests to measure the integrity of flanged junctions in the Oil & Gas and fuel industries, in order to ensure the safety of the facilities and protect the environment, water and nature in general. If a pipeline is designed to operate at a certain pressure, this test must be performed beforehand to know if it is structurally able to withstand the internal pressurerequired.

How is a hydrotest performed?

A Hydrotest or Hydrostatic Test consists of several steps:

  • The test object is placed in a steel chamber simulating a real installation for the test bench.
  • First, the pipe is filled little by little with the precise amount of water needed to fill the line.
  • Air is expelled from the line as it is filled, as it can cause excessive pressure. For this purpose, automatic air release valves or suction cups can be installed.
  • Then the pressure of the pipe, fittings and anchors is checked to ensure it is not over limits.
  • Pressurized water is pumped into the vessel, which will expand forcing the air out of the chamber, releasing the pressure.
  • In case of pressure loss, the test must be repeated until it performs acceptably.
  • The pipeline is emptied carefully, removing the water or liquid in appropriate ways that do not affect the environment.
  • The area is properly cleaned, removing the equipment and tools used.

This test can last up to twelve hours, during which the system must not experience a pressure drop of more than 0.20 bars.

At our in-house facilities at ULMA Forged Solutions, we perform all types of destructive and non-destructive tests to check the proper condition of our materials. We also perform and report on the hydrotest test for those flanges that are non-standard and designed internally in order to ensure integrity and zero leakage in the flanged junction and validate the design.