Pressure Test with Gas – How to Pneumatically Test Vessels & Piping

Published 2026-10-17 · Jinan Shangling Technology Co., Ltd.

A pneumatic (gas) pressure test verifies the strength and leak-tightness of pressure vessels, piping and valves using air or nitrogen. Unlike hydrostatic testing, it needs no draining and can be used where water must not enter the system – but compressed gas stores far more energy, so the procedure must be strictly controlled.

1. Pneumatic Test Pressure Rules

1. Pressure vessels: per ASME BPVC Section VIII Div.1, the pneumatic test pressure is 1.1 times the design pressure (with the stress ratio correction), and per GB/T 150-2011 about 1.15 times for carbon/low-alloy steel;
2. Process piping: per ASME B31.3, pneumatic test pressure is 1.1 times the design pressure; per GB 50235-2010, 1.15 times for above-ground piping;
3. Valves: shell strength test at 1.5 × rated pressure, seat seal test at 1.1 × rated pressure (per product standards).

2. Staged Pressurization

Pneumatic testing must always be staged:

1. Below 1.6 MPa: pressurize in two stages (0.5×, 1.0× test pressure);
2. Above 1.6 MPa: three stages (0.5×, 0.8×, 1.0×), holding 3-5 minutes at each stage for inspection;
3. At test pressure, hold for 10-30 minutes – no leakage, no deformation and a stable reading mean a pass.

3. Safety Requirements

Set up a barricaded test area with restricted access; never use oxygen as the test medium (explosion risk); do not hammer or tighten bolts during pressurization; stop and vent immediately on abnormal noise or sudden pressure drop.

4. Pressurization Equipment

High-pressure cylinder banks are heavy and cannot deliver a steady, adjustable pressure. A gas booster pump intensifies a low-pressure source (0.5-15 MPa) to the required test pressure with continuous adjustment, auto stop at set point, and computer-controlled test curves – ideal for repeatable batch testing.

5. Shangling Solution

Jinan Shangling Technology supplies gas booster pumps, pneumatic test benches and automatic test systems up to 100 MPa, oil-free compression, auto pressure-holding and recording, and custom designs per specimen and standard. For more details, please call 18668913679 or email ljys@163.com.