Safe Isolation Without System Drain Down
ProMech provides specialist liquid nitrogen pipe freezing, allowing maintenance, repairs and system modifications to be completed without draining pipework or shutting down entire systems.
By creating a temporary ice plug inside the pipeline, we isolate a section of pipe while the rest of the system stays in operation. On a large building that is the difference between replacing one valve and draining several thousand litres, refilling, redosing and recommissioning a circuit that was working perfectly well the day before.
It matters most where a shutdown is not really available. An occupied hospital wing, a running production line, a tenanted building in winter, a data hall that cannot lose cooling. Our engineers carry out every freeze using proven procedures, specialist equipment and full safety controls across Northern Ireland, Dublin and London.
Our Process
- 1
Survey and freeze point selection
We confirm pipe material, wall thickness, diameter, contents and temperature, then choose a freeze point on a straight run clear of valves, welds and fittings. Not every position on a pipe is suitable, and picking the wrong one is how freezes fail.
- 2
Flow confirmation and system preparation
Circulation through the target section must be stopped. An ice plug will not form in moving water, so the relevant pump or circuit is confirmed off and verified at the freeze point before any nitrogen is applied.
- 3
Risk assessment, RAMS and area control
A written method statement and risk assessment covering the freeze, the nitrogen handling and the work to follow. The area is controlled, ventilation assessed and oxygen depletion monitoring put in place before work begins.
- 4
Jacket fitting and nitrogen application
A freeze jacket sized to the pipe is fitted and sealed, then liquid nitrogen is introduced in a controlled manner to draw heat out of the pipe wall and the water inside it.
- 5
Plug formation and verification
Temperature is monitored as the plug forms. The freeze is proven before anything is broken into, so the section is opened against a verified isolation rather than an assumed one.
- 6
Mechanical works under maintained freeze
Nitrogen is topped up to hold the plug for the duration of the task while the valve, strainer, tee or repair is carried out. The rest of the system stays live throughout.
- 7
Controlled thaw and reinstatement
Once the joint is closed, the plug is allowed to thaw under control rather than forced. The section is vented, refilled where required, checked for leaks and returned to service.
- 8
Documentation and handover
You receive the RAMS, the freeze record, monitoring data and details of the work carried out, which matters on regulated sites where the intervention has to be evidenced.
Work We Carry Out Under Freeze
Systems We Work On
- Chilled Water (CHW)
- Low Temperature Hot Water (LTHW)
- Condenser Water
- Heating Water
- Glycol Systems
- Potable Water
- Industrial Process Water
Industries We Support
- Data Centres
- Pharmaceutical Facilities
- Manufacturing Plants
- Commercial Buildings
- Hospitals
- Energy & Utilities
- Industrial Processing
Standards & Compliance
- COSHH, assessment and control of the nitrogen hazard
- Confined Spaces Regulations 1997, where the work falls within one
- Oxygen depletion monitoring for the duration of every freeze
- CDM 2015 site safety protocols
- ISO 9001 documented procedures and records