In many Line & Equipment Opening (LEO) safe work practices, some leeway will be granted to the workers AFTER the INITIAL “break” based on the level of ISOLATION they have protecting them. For example: A LEO has a double block and bleed arrangement on BOTH sides of the opening. During the initial “break,” the worker(s) will wear ALL PPE, at a level that assumes the line/equipment is FULL and UNDER PRESSURE. After a successful opening, and given that the workers are protected by the DB&B isolation, they may remove some PPE. However, as in the case discussed below, when the isolation is a single valve on either side (or both), then this level of isolation does NOT afford a level of protection such that the PPE can be lessened after the first break, REGARDLESS if that initial break is successful (e.g., no leak by).
A global chemicals company has been fined £400,000 after a worker narrowly escaped serious injury in a high-pressure steam release incident. The company was fined after the 59-year-old contractor, working under its control and direction, carried out unsafe maintenance work. The man was working as a mechanical fitter on November 6, 2023, when the incident occurred, prompting the company to report it to the Health and Safety Executive (HSE) as a dangerous occurrence. The incident involved a release of high-pressure steam while he was performing his job.
The company operates a large agrichemicals production site, with some production plants relying on high-pressure steam to manufacture products. The HSE investigation found that the incident occurred during the planned replacement of a faulty steam trap on small-bore pipework.
Steam traps are devices that automatically remove condensate (water) and air from the high-pressure steam system. There was a sudden failure of the valve isolating the work location from the steam, resulting in an uncontrolled high-pressure release.
The HSE investigation also revealed several failures with the system of work in operation. These included:
- The isolation valve failed when the mechanical fitter was separating a bolted flange by cutting the bolts using a battery-powered reciprocating saw.
- The isolation valve and flange bolts were corroded and in poor condition.
- Due to widespread corrosion of flange bolts on the steam distribution system, it was considered necessary to routinely cut bolts rather than unscrew them using a spanner.
- Cutting flange bolts reduces the ability to control any unexpected, trapped material or pressure remaining in the pipework.
The company pleaded guilty to failing to ensure that the isolation valve and flange bolts were maintained in an efficient state, in efficient working order, and in good repair, as required by Regulation 5(1) of the Provision and Use of Work Equipment Regulations 1998 (PUWER), HSE.
In addition, there was an issue with the company’s documented risk assessment procedure in place prior to the maintenance work. It was routine for the facility to carry out maintenance work on small-bore pipework of the high-pressure steam distribution system, using a SINGLE method of isolation.
HSE’s published guidance on this subject (The safe isolation of plant and equipment – HSE, HSG253) emphasizes that using a method of double isolation is safer. The risk assessment documents in place failed to appreciate the increased risk involved in relying on a single method of isolation when there was known corrosion of the work equipment.