Preventing entrapment in plastics rotational moulding ovens where there is whole body access

Health and Safety Executive - Safety alert

Department Name:
OPSTD – General Manufacturing Section – Plastics

Bulletin No:
OPSTD 1-2014

Issue Date:
24 July 2014

Target Audience:

  • Manufacturing (General)
  • Plastics industry - Rotational Moulders

Key Issues:
This safety notice is about the risks of entrapment where there is whole body access into rotational moulding ovens during maintenance or other machine interventions. On some ovens it has been found that it is possible for an operator to be trapped inside the oven as a result of poor machinery design, unsafe procedures and no means of escape being provided.  All users of rotational moulding ovens should review what measures they have in place to prevent a person becoming trapped in their oven and take remedial action in line with this safety notice.


This safety bulletin is being issued following a fatality in a plastics rotational moulding oven.  This information is issued without prejudice to any ongoing investigations.

HSE is using this alert to raise awareness of the issue of whole body entrapment inside rotational moulding ovens and to urge users of these machines to review their moulding machines and procedures to ensure whole body entrapment is not possible through:


Rotational moulding ovens are used to melt plastic powders or granules that are placed in a mould, which is then heated whilst being rotated and in some cases rocked. As the plastic melts it coats the inside of the mould to form the product being manufactured. Products being manufactured in this way range from small to very large items. Consequently, the ovens the mould is rotated in can vary greatly in size and some are big enough for whole body access and sometimes have conveying systems to carry the mould into the oven, The introduction of conveyor systems in any oven increases the likelihood of access into that oven in order to carry out either routine or breakdown maintenance on the conveyor system. In addition, as the plastic sometimes drips out of the mould during production there is a need for people to enter the oven to clean the residue off or to enter the oven for other maintenance reasons.

HSE has identified that on some rotational moulding ovens where there is the potential for whole body access there is a risk of entrapment. The consequences of a person becoming trapped inside an oven, which is then heated up, is almost certain death due to the high temperatures that the ovens can reach.

A number of factors are present that contribute to the risk of entrapment as follows:

Action required

Users of machines with whole body access and the risk of entrapment should now carryout a risk assessment of their machines and procedures to ensure they have adequate control measures in place.  The risk assessment should consider the likelihood of getting trapped inside the oven, how a person could escape if they were trapped and the package of control measures that need to be in place to prevent this.  The factors outlined in this safety notice along with any other relevant factors should be considered as a part of the risk assessment process and the correct combination of controls for your machine should be put in place. Control measures may include:

Whatever measures your risk assessment identifies you should ensure they are designed so that a person who is trapped within the oven is able to find and use them, eg if it were dark lighting may be needed etc.

Safe systems of work – when carrying out your risk assessment you should ensure that robust safe systems of work are in place that accurately consider and reflect your machine operation and procedures. The safe systems of work should include, but not be limited to isolation and oven entry procedures. Once established, appropriate information, instruction, training and supervision should be provided to all staff to ensure that the risk of entrapment is controlled.

Relevant legal documents



Further information

Health and Safety Executive
OPSTD Manufacturing Sector - Plastics
Foundry House
3 Millsands
Riverside Exchange
S3 8TH

General note

Please pass this information to a colleague who may have this equipment or operate this type of process.