Pressure & Hydrostatic Testing

Pressure and hydrostatic testing on board

Pressure and hydrostatic testing verifies that piping, hoses, pressure vessels and heat exchangers can hold their test pressure without leakage or permanent deformation. On ships it is required after repairs and modifications, during class surveys, when leaks are suspected, and as part of routine fire-fighting equipment maintenance. A properly planned test also avoids the common pitfall of damaging instruments, valves or gaskets that were not designed to see test pressure.

This service covers ship systems and components. Gas cylinders such as SCBA, CO2 and fire extinguisher cylinders follow their own testing regime and are handled under cylinder hydrostatic testing and recharging. vslSafety coordinates providers who supply test pumps, calibrated gauges, blanks and personnel for testing at the vessel’s port.

Regulatory requirements and standards

• Class rules set hydraulic test pressures for piping, pressure vessels and heat exchangers after manufacture, installation and repair. For many piping systems the test pressure is 1.5 times the design pressure, but the exact figure depends on the system, class rules and design code.
• Fire hoses – MSC.1/Circ.1432 calls for an annual pressure test of a sample of fire hoses at the maximum fire main pressure, so that all fire hoses are tested within five years. Fire pumps are flow tested annually and hydrant valves are tested for operation.
• Pressure vessels – air receivers, boilers and other pressure vessels are examined at class machinery surveys; hydraulic tests may be required after repairs or where internal examination is not possible. Flag and national regulations may add their own requirements.
• Heat exchangers – coolers and condensers are pressure tested after retubing, plugging or repair to confirm tube and plate integrity.
• Gauges used for testing should be calibrated and of a suitable range, with calibration certificates available to the surveyor.

Flag and class requirements vary, so the test pressure, hold time and acceptance criteria should be agreed with the surveyor before testing.

Testing intervals and triggers

Item	Requirement	Interval	Reference
Fire hoses	Pressure test at maximum fire main pressure (sample)	Annual, all hoses within five years	MSC.1/Circ.1432
Fire pumps	Flow test for pressure and capacity	Annual	MSC.1/Circ.1432
Piping after repair or modification	Hydrostatic test to class test pressure	After work, before return to service	Class rules
Pressure vessels and air receivers	Examination and, where required, hydraulic test	At class machinery surveys and after repair	Class rules, flag
Heat exchangers	Pressure test of tubes or plates	After retubing, plugging or leak repair	Class rules, maker

What the service includes

• Review of system design pressures and class test requirements, and preparation of a test procedure
• Supply of manual or powered hydrostatic test pumps, blanks, flanges and adaptors
• Calibrated test gauges and pressure recorders with certificates
• Isolation of instruments, relief valves and components not rated for test pressure
• Filling, venting, pressurising, holding and inspecting for leaks and deformation
• Fire hose pressure testing, marking and record-keeping
• Heat exchanger shell and tube side testing and leak location
• Pneumatic leak testing where hydraulic testing is not suitable and it is permitted
• Draining, reinstatement and test report

Systems and equipment covered

Fire mains and hydrants, fire hoses, sprinkler and water spray piping, ballast, bilge and fuel oil piping, cargo lines on tankers, steam and condensate lines, compressed air systems and air receivers, heat exchangers (shell and tube, plate type), fresh water generators, hydrophore tanks and calorifiers. Boiler work is covered under boiler and economiser servicing, and fire-fighting equipment under fire fighting systems and equipment.

Common defects and PSC deficiencies

• Fire hoses without test records, or hoses with perished linings and damaged couplings
• Fire main leaks and temporary repairs with clamps or wrapping, which PSC treats as a serious deficiency
• Fire pumps unable to deliver the required pressure at the hydrants
• Corroded pipe sections failing at test, often in ballast, bilge and fire main lines
• Heat exchanger tube leaks causing contamination between systems
• Gauges without calibration or of unsuitable range

Certificates and documents you receive

A pressure test report for each system or component, stating test medium, test pressure, hold time, gauge identification and calibration, and result; a fire hose test log with hose identification; photographs of leaks found; and recommendations for repair. Gauge calibration certificates are attached. Where class witnesses the test, the report supports the surveyor’s own record.

How to prepare the vessel

• Identify each system and component to be tested, and confirm design pressures from drawings
• Arrange isolation and drain points, and plan how test water will be disposed of
• Remove or blank instruments and relief valves that cannot see test pressure
• Number and list all fire hoses with their last test dates
• Book class attendance if the test must be witnessed

Information needed for a quotation

• Vessel name, IMO number, flag and class
• Port, berth or anchorage, ETA and ETD
• Systems or components to be tested, with sizes, lengths and design pressures
• Number of fire hoses and their sizes and coupling types
• Heat exchanger type, maker and dimensions if applicable
• Reason for testing: repair, survey, routine maintenance or leak investigation
• Whether class or flag attendance is required

vslSafety coordinates a suitable testing provider at the vessel’s port and aligns the test with the surveyor’s attendance.

Frequently asked questions

How often should fire hoses be pressure tested?

MSC.1/Circ.1432 recommends an annual pressure test of a sample of fire hoses at the maximum fire main pressure, arranged so that all hoses on board are tested within five years. Some flag Administrations require all hoses to be tested annually, so check the flag’s instructions. Each hose should be identified so that test history can be tracked.

What test pressure is used for ship piping?

For many piping systems class rules require a hydraulic test at 1.5 times the design pressure after manufacture or repair, but the factor depends on the system, class and design code. Some systems, such as steam or fuel oil lines, have specific requirements. The surveyor should agree the test pressure and hold time before the test.

Can pneumatic testing replace hydrostatic testing?

Pneumatic testing stores much more energy than hydrostatic testing and is therefore more dangerous if a component fails. It is normally used only where water cannot be introduced into the system, at lower pressures and with strict precautions. Class approval is generally needed where a pneumatic test replaces a required hydraulic test.

Is the fire main hydrostatically tested?

Fire mains are tested in service through regular pressure and flow checks and fire pump tests under MSC.1/Circ.1432, and hydrostatically after repairs or pipe renewal to class requirements. Some flags or companies require periodic hydrostatic tests of the fire main, so check flag instructions and the SMS.

Why should gauges be calibrated for pressure testing?

The test result is only as reliable as the gauge. An uncalibrated gauge can under- or over-state pressure, risking either an invalid test or damage to the system. Surveyors expect calibration certificates, which can be arranged through calibration services.