Updated Flexigas guidance
This older article is retained because installers and specifiers still search this topic. For current Flexigas guidance, compare CSST with rigid copper and steel routes, then use the installation guide for cutting, jointing, bonding and testing detail.
BSI Kitemark KM 598726 | BS EN 15266:2007 | MOP 0.5 bar | DN15-DN50 | Gas Safe/ACS context
Current comparison
Most gas pipework methods are selected around route complexity, joint count, working method, standards context and installer competence. Copper and threaded steel remain established rigid options. Flexigas CSST can be useful where a certified flexible fixed-pipework system helps reduce joints and route around obstructions, but final selection must be sized and installed by a competent Gas Safe registered engineer using current guidance.
| Method | Where it can fit | What to check |
|---|---|---|
| Copper pipework | Established rigid pipework for accessible domestic routes and short, simple runs. | Check hot works, fittings, concealed joints, disruption, supports and sizing. |
| Threaded steel or iron | Often used where a robust exposed route, plant room or project specification calls for it. | Check fabrication time, threading, corrosion protection, supports and the project standard. |
| Flexigas CSST | Certified flexible fixed gas pipework where route complexity, joint reduction and less hot work are important. | Check sizing, bonding, support, protection, testing and use Flexigas tubing and fittings as a system. |
For Flexigas, BS 6891:2015 applies across the DN15-DN32 domestic pipework context noted by Flexigas. DN40/DN50 and work above that scope should be checked against the relevant IGEM/UP/2 or project design context.
No. Flexigas CSST is a fixed gas pipework system. It should not be treated as a loose appliance hose.
No. Pipe size must be calculated from connected load, route length, equivalent fittings, gas type, pressure drop and the applicable standard.
Gas work must be carried out by a competent Gas Safe registered engineer with the relevant ACS or allied qualification context and current Flexigas guidance.
No. Use Flexigas tubing and Flexigas fittings as a system. Do not mix Flexigas CSST or fittings with other manufacturers' CSST systems.
Ask before unusual routes, DN40 or DN50 work, commercial jobs, voids, tight pressure-drop limits or any standards question that is not clear from the current documents.