Leak Testing Services

Leak testing establishes whether a pressure boundary holds — and where it does not, the location and size of the breach. The methods available span roughly six orders of magnitude in sensitivity, so selecting the right one matters more than performing it well: a test far more sensitive than the specification requires wastes time and money, and one less sensitive gives a pass that means nothing.

Methods

• Bubble emission — direct pressureThe item is pressurised and either immersed or coated with a surfactant solution. Bubbles form at a through-wall defect, showing both presence and exact location. Fast, low cost and well suited to weld seams, fittings and flanges.
• Bubble emission — vacuum boxWhere the item cannot be pressurised, a vacuum box is placed over a wetted surface and evacuated. Applied to tank floors, roof plates and weld seams accessible from one side only.
• Pressure decayThe system is pressurised, isolated and monitored over a defined hold period, with temperature compensation applied. Establishes overall integrity but does not locate the leak.
• Vacuum decayThe reverse, used where pressurising is impractical or unsafe. Suited to closed vessels, jacketed equipment and systems that normally operate under vacuum.
• Fluorescent dyeA fluorescent tracer is introduced into the system and the external surface examined under UV-A. Effective for finding small leaks in complex geometry and in hydraulic, fuel and lubrication systems where a slow weep would otherwise take days to appear.
• Tracer gas detectionHelium or hydrogen mixtures introduced to one side and detected on the other. Orders of magnitude more sensitive than bubble methods, used where the consequence of a small leak is severe.

Testing alongside hydrostatic and pneumatic tests

Leak testing is frequently carried out in conjunction with a hydrostatic or pneumatic strength test, but the two answer different questions. A hydrostatic test proves the pressure boundary can withstand the applied load; it does not reliably detect small leaks, because water surface tension holds back defects that will pass gas in service. Where a specification requires both, the leak test is normally performed at a lower pressure with a method matched to the leak rate of interest.

Selecting the method

Selection depends on the acceptable leak rate stated in your specification, whether the item can be pressurised or evacuated, whether it can be wetted, access to both sides of the boundary, and the consequence of the fluid escaping in service. Where the specification names a method we apply that method. Where it states only an acceptance criterion, we select a technique capable of resolving it and record the justification — a test that cannot detect a leak at the specified threshold does not demonstrate compliance regardless of the result.

Standards applied

• ASME Boiler and Pressure Vessel Code, Section V, Article 10 — leak testing, with acceptance to the relevant construction code section
• ASTM E432 — selection of a leak testing method
• ASTM E515 — bubble emission techniques
• ASTM E1003 — hydrostatic leak testing
• ISO 20485 — tracer gas method
• Client, project and manufacturer specifications, and in-house procedures where these govern

Where it applies

• Pressure vessels, tanks and storage systems
• Pipework, pipelines and spools
• Valves, flanges and fittings
• Heat exchangers and condensers
• Hydraulic, fuel and lubrication systems
• Fabrication and pre-shipment verification
• Post-repair confirmation after weld repair or component replacement

Related services

Where the required sensitivity exceeds what bubble or decay methods can resolve, helium mass spectrometry is covered separately, as is tube-by-tube leak location in heat exchangers and vacuum box testing of tank floors and weld seams.

Accreditation and approvals

ITMAD is accredited to ISO/IEC 17020 as an inspection body, is an ADNOC approved inspection contractor, and is listed on the Abu Dhabi City Municipality register of Approved Third Party Inspection Bodies. Certificates are issued in the format required by the governing authority, including Dubai Municipality and the Dubai free zone authorities, and inspection is carried out across Dubai, Abu Dhabi, Sharjah and the northern Emirates. Testing is performed by qualified NDT technicians at your site, in fabrication yards or offshore.

What you receive

• A report identifying the item tested, method applied and test parameters
• Hold period, pressure and temperature compensation where a decay method was used
• Location of each indication found, with photographic evidence
• Assessment against the acceptance criteria in your specification
• Technician qualification and instrument calibration traceability