Pressure equipment

Many types of pressure equipment can be hazardous. These include steam boilers and associated pipework, pressurized hot-water boilers, air compressors, air receivers and associated pipework, autoclaves, gas storage tanks and chemical reaction vessels.

When things go wrong, these types of equipment can cause serious injuries and even fatalities. However, assessing the risks and putting proper precautions in place will minimize the chances of any accidents occurring.

Case study
A company used a steam boiler in its manufacturing processes. An alteration to pipework inadvertently caused salty water to be introduced into the boiler.

The resulting build-up of scale caused its furnace to overheat and collapse internally, creating an explosion. This blew out the ends of the boiler house and the ejected boiler demolished an electrical substation hundreds of feet away before coming to rest.

How the accident could have been prevented

This accident could have been prevented by giving the maintenance staff correct information and instruction, and by adequately managing the maintenance operation.

As a result of the damage to the building, its contents and exterior damage, the company had to replace the boiler and rebuild the boiler house, with significant loss of production.

Why is pressure equipment safety important?

If a piece of pressure equipment fails and bursts violently apart, the results can be devastating to people in its vicinity.

Parts of the equipment could also be propelled over great distances, causing injury and damage to people and buildings hundreds of metres away.

What should employers do?

Assess the risks

Employers need to assess the levels of risk when working with pressure equipment. The level of risk from the failure of pressure systems and equipment depends on a number of factors including:
  • the pressure in the system;
  • the type of liquid or gas and its properties;
  • the suitability of the equipment and pipework that contains it;
  • the age and condition of the equipment;
  • the complexity and control of its operation;
  • the prevailing conditions (e.g. a process carried out at high temperature);
  • the skills, knowledge and experience of the people who maintain, test and operate the pressure equipment and systems.

Basic precautions

To reduce the risks employers need to know (and act on) some basic precautions:
  • Ensuring the system can be operated safely, for example without having to climb or struggle through gaps in pipework or structures.
  • Being careful when repairing or modifying a pressure system. Following a major repair and/or modification, they may need to have the whole system re-examined before allowing the system to come back into use.
  • Providing a set of operating instructions for all of the equipment in the system and for the control of the system as a whole, including in emergencies.
  • Guaranteeing there is a maintenance programme for the system as a whole. It should take into account the system and equipment age, its uses and the environment in which it is being used.

Written scheme of examination

With regards to maintenance a written scheme of examination is extremely useful for pressure systems:
  • This should be drawn up (or certified as suitable) by a competent person – someone who has the necessary skills, knowledge and experience to carry out the work safely.
  • It should cover all protective devices, every pressure vessel and those parts of pipelines and pipework which, if they fail, could be dangerous.
  • The written scheme should specify the nature and frequency of examinations, and include any special measures that may be needed to prepare a system for a safe examination.
  • Legislation may require pressure systems to be examined by competent persons within predetermined timescales, these examinations should be in addition to regular and routine maintenance.

How can employers do it?

  • First of all, they should consider whether the job can be done another way without using pressure equipment, for example using vacuum equipment for cleaning rather than compressed air. If they have to use pressure equipment, they should not use high-pressure equipment when low-pressure will do.
  • Ensure that they buy pressure equipment that complies with the relevant product regulations.
  • Before using pressure equipment, employers where possible should ensure that they have obtained a written scheme of examination. Also making sure that any inspections needed have been completed by a competent person, and that the results have been recorded.
  • They should always operate the equipment within the safe operating limits. If these are not provided by the manufacturer or supplier, a competent person can advise them.
  • They should provide instruction and relevant training for the workers who are going to operate the pressure equipment and also include what to do in an emergency.
  • Employers should have an effective maintenance plan in place, which is carried out by appropriately trained people.
  • Guaranteeing that any modifications are planned, recorded and do not lead to danger.

Find out more
  1. HSE’s website on pressure systems  
  2. Pressure systems: A brief guide to safety