Pre-commissioning refers to a set of activities performed after construction and
before the official commissioning of a plant, system, or piece of equipment. The
goal is to ensure everything is installed correctly, clean, leak-free, and ready for safe
operation.
Inspection
Verifying proper installation of piping, valves, instruments, and equipment.
Checking alignment, supports, welding quality, etc.
Cleaning
Flushing, blowing, or chemical cleaning of pipes and equipment to remove debris.
Hydrotesting / Pressure Testing
Pressurizing systems with water or inert gas to check for leaks and verify strength.
Drying and Purging
Removing moisture or air from the system (important in gas or steam systems)
A pneumatic test is a pressure test that uses a gas (usually air or nitrogen) to check the strength and leak-tightness of a system such as pipelines, pressure vessels, valves, or tanks.
It is an alternative to hydrostatic (water-based) testing, used when water cannot be used due to material compatibility, cleanliness requirements, freezing risk, or when drying the system would be difficult afterward.
Feature
Pneumatic Test
Hydrostatic Test
Test Medium
Air, nitrogen, or dry gas
Water
Risk Level
Higher (gas is compressible-
more energy)
Lower (water is incompressible
Sensitivity
Can detect smaller leaks
Less sensitive unless with leak detection add-ons
Preparation
No drying needed afterward
Requires drying if system must stay dry
Standard Metode and Reference
ASME Section VIII Div. 1
Vessels
ASME B31.1 / B31.3
Pipping systems
EN 13445 / EN 13480
European standards
ISO 20485 / ISO 13628
Various equipment-specific standards
Helium Leak Testis a high-sensitivity leak detection method that uses helium gas as a tracer to detect very small leaks in sealed systems such as pressure vessels, heat exchangers, piping, valves, vacuum systems, and electronic components.
It is widely used because helium is inert, non-toxic, has small molecules, and is easy to detect atvery low concentrations.
Low natural background concentration in air (-5 ppm) easy to detect.
Can detect leaks as small as 1 x 10-12 mbar•L/s, much more sensitive than soap bubble or pneumatic tests.
Method
How It Works
Common Use
Vacuum (Inside-Out)
Object is pressurized with helium inside, outside is vacuum.
Sealed vessels, electronic enclosures
Sniffer (Outside-In)
Object is pressurized with helium; sniffer probe scans outside.
Valves, welds, pipe joints
Spray Probe (Outside-Out)
Vacuum inside part; helium is sprayed around suspect areas.
Flanges, seals, glass-to-metal seals
Accumulation Testing
Helium accumulates in a chamber around the test object.
Large objects or low-rate leaks
Bubble Testing with Helium/Nitrogen Mix
Not as sensitive, but used in field tests.
Gross leak detection (visual only)
Standard Metode and Reference
ASME V Article 10
Leak Testing with helium mass spectrometer.
ISO 20485
Non-destructive testing – Leak testing – Tracer gas method.
EN 13185/EN 13192
Leak detection using helium.
ASTM E498 / E499 / E1003
Helium leak testing standards.