Asbestos pipe lagging

What pipe lagging actually is

Two forms turn up again and again. The first is a wet mixture of asbestos with magnesia or calcium silicate, trowelled on by hand around bends, valves, flanges and calorifier bodies, then finished with a scrim or canvas skin and painted. The second is preformed sectional insulation, half-round mouldings clamped around straight pipe runs and held with bands, wire or cloth. Bends and valve bodies were often boxed in with a hand mix even where the straights were sectional, so a single pipe run can be part asbestos and part not.

The fibre used in insulation was frequently amosite or crocidolite rather than chrysotile, which is why the material sits in the licensed category. Installation was heaviest from the 1950s into the early 1970s, tailed off after the Asbestos Regulations 1969 tightened control, and the amosite and crocidolite import ban of 1985 followed by the 1999 ban on chrysotile closed the door on the rest. Check any date against current HSE guidance before you rely on it in a report. What the dates do not tell you is that plenty of buildings kept old stock in the stores and used it well after the fashion turned.

Colour tells you nothing useful. A grey-white magnesia mix and a blue-grey one can both contain amosite, and repainting over forty years hides everything anyway. The give-away is more often the shape than the substance: a pipe that is oddly fat at a bend, a valve encased in a lumpy plaster block, a hard painted shell that sounds hollow and gives slightly under a fingertip. That is the point at which you stop, not the point at which you investigate further.

Where I find it

Plant rooms and boiler houses are obvious. The finds that catch people out are the concealed ones: a redundant run boxed in behind plasterboard during a 1990s refit, a stub of lagging left on a bracket after a stripping job that was paid by the metre, a service tunnel between two blocks that nobody has entered since the district heating was decommissioned. Residues around difficult joints are the single most common thing I see on pipework that has supposedly been cleared.

• Boiler houses, plant rooms, cellars, basements and service tunnels.
• Risers, ceiling voids, heating ducts and under-croft runs in blocks of flats.
• Schools, hospitals, mills and public buildings with original heating systems.
• Behind later boxing, dry lining and non-asbestos insulation applied over the top.

Treat a clean-looking pipe with suspicion if the paperwork is thin. Re-insulated pipework proves that somebody applied new insulation, not that they removed the old.

Why lagging behaves differently to other asbestos

Asbestos cement holds its fibres in a hard matrix and needs cutting or breaking to release much. Lagging does not. Under the painted skin the material can have the consistency of chalk or damp cardboard, and the fibres are barely held at all. A knock from a ladder, a cable pulled through a void, a boot on a pipe used as a step, and you have a release. HSE guidance places insulation among the highest fibre release potential of any asbestos-containing material, which is the reason for the licensing regime around it.

The deterioration I see most is not vandalism, it is water. A weeping joint above a run of magnesia insulation turns it to porridge, it slumps, the skin splits and the debris lands on the floor below. After that come vibration at brackets, rodent activity in ducts, and the maintenance engineer who needed to get at one valve and cut the lagging back to reach it. Once the skin is broken, every subsequent visit to that plant makes it worse.

If you want a general sense of what you are looking at before you decide to stop work, what does asbestos look like gives visual context. Use it to recognise when to down tools, not to reach a conclusion.

Licensed work, and what competent actually means

Work on asbestos insulation normally requires a contractor holding a licence from the Health and Safety Executive under the Control of Asbestos Regulations 2012, and the work is normally notifiable with advance notice to the enforcing authority. Narrow exceptions exist, including properly controlled sampling by a competent person, but nobody should read those exceptions as permission for a plumber or a homeowner to cut a piece out.

Where licensed removal happens, plan the clearance before the enclosure goes up rather than after. Four-stage clearance and any air testing must be done by an analyst independent of the removal contractor, working for an organisation accredited by UKAS for that activity. If the same firm is stripping the pipe and signing off the air test, that arrangement is wrong and the certificate is worth very little.

Asbestos awareness training exists so that people stop when they meet asbestos. It does not qualify anyone to touch lagging, and I have seen the certificate produced as though it did.

Surveys and sampling on friable insulation

HSG264 sets the expectation that the survey suits the building and the intended work. A management survey will record accessible lagging, score its condition and set out how it is protected while the building is in use. A refurbishment or demolition survey has to get into what the project will disturb, which on heating work means opening boxing, entering ducts and chasing redundant runs that nobody has drawn for thirty years. A management survey handed over as though it covered a boiler replacement is a common and expensive mistake.

Sampling friable insulation needs controls appropriate to the material: local containment, wetting, controlled removal of the smallest workable piece and proper repair of the hole afterwards. The sample goes to a laboratory accredited by UKAS to ISO/IEC 17025 for asbestos identification. The roles of sampler and laboratory are set out on the asbestos testing page.

Duties, and where domestic property sits

In non-domestic premises and the common parts that go with residential blocks, the dutyholder under regulation 4 of CAR 2012 has to take reasonable steps to find out whether asbestos is present, assess its condition, keep the information current and pass it to anyone liable to disturb it. A plant room with lagging in it is precisely the case regulation 4 was written for.

A private homeowner does not usually carry the regulation 4 duty inside their own home. The regulations still bite on the employer or contractor doing work there. So before a boiler swap, a heating alteration or the opening up of pipe boxing, suspected insulation needs identifying and building into the plan, whoever owns the building.

If it has already been disturbed

Stop, walk out, keep others out and leave everything where it is. Do not sweep, do not hoover, do not bag up the debris and do not take tools or clothing out of the area to deal with later. Contaminated overalls carried through a building spread the problem into places nobody will think to check.

Tell whoever is responsible for the premises and get competent advice the same day. What follows may involve assessment of the spread of contamination, controlled cleaning under licence and a record of who was exposed and for how long. The first steps are set out on the suspected asbestos page.