HSE OCE9 Use of Drilling Muds (Shale Shaker and Mud Pit Areas)

Controlling Exposure to Drilling Muds, Mists and Vapours During Offshore Drilling Operations

LEVCentral Expert Commentary

Drilling mud systems are fundamental to modern oil and gas drilling operations. They cool and lubricate the drill bit, transport drill cuttings to the surface, stabilise the borehole and control formation pressures. However, the handling and circulation of drilling muds can also expose workers to a complex mixture of chemical additives, drilling fluids, mists, vapours and aerosols, particularly around shale shakers and mud pit areas.

HSE OCE9 – Use of Drilling Muds (Shale Shaker and Mud Pit Areas) forms part of the Offshore COSHH Essentials (OCE) series and provides practical guidance on controlling these exposures. The guidance covers routine activities including mud handling, sampling, equipment cleaning and maintenance, with particular emphasis on applying good engineering controls as part of a COSHH assessment.

For LEV professionals, OCE9 is particularly interesting because it demonstrates the application of Local Exhaust Ventilation (LEV) in a demanding industrial environment. Shale shakers continuously release mists and vapours as drilling fluids are separated from drill cuttings, making effective enclosure, extraction and good ventilation essential components of exposure control.

The guidance also illustrates a broader occupational hygiene principle:

Where contaminants are generated continuously during a process, engineering controls should be integrated into the process itself rather than relying on personal protective equipment alone.

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Key Learning Points

The guidance covers:

Health hazards associated with drilling muds.
Exposure to drilling fluid mists and vapours.
Shale shaker operations.
Mud pit areas.
Mud handling and sampling.
Cleaning and maintenance activities.
Enclosure of mud handling equipment.
Application of Local Exhaust Ventilation (LEV).
General ventilation requirements.
Good housekeeping.
Personal protective equipment (PPE).
Respiratory Protective Equipment (RPE) where appropriate.
Inspection and maintenance of engineering controls.
Information, instruction and training for workers.

Source Document Information

Organisation: Health and Safety Executive (HSE)

Document: OCE9 – Use of Drilling Muds (Shale Shaker and Mud Pit Areas)

Series: Offshore COSHH Essentials (OCE)

Document Type: COSHH Essentials Guidance Sheet

Primary Topics: Drilling Muds, Shale Shakers, Local Exhaust Ventilation, Offshore Drilling, COSHH, Occupational Hygiene

Audience: Offshore Drilling Contractors, Drilling Supervisors, Occupational Hygienists, LEV Designers, Health & Safety Professionals, Process Engineers and Duty Holders.

LEVCentral Perspective

Although written specifically for offshore drilling operations, OCE9 demonstrates principles that apply to many industrial processes involving continuous release of mists and aerosols.

One of the most valuable aspects of the guidance is its emphasis on controlling contaminants at source. Shale shakers represent a predictable and continuous emission point, making them well suited to engineering controls such as enclosure and local extraction. Rather than attempting to dilute contaminants after they have dispersed into the workplace, OCE9 promotes capturing them where they are generated.

The guidance also reinforces that successful exposure control rarely depends upon a single measure. Effective protection is achieved through a combination of:

process enclosure;
Local Exhaust Ventilation (LEV);
good general ventilation;
safe sampling procedures;
competent maintenance;
good housekeeping; and
appropriate PPE and RPE where residual risks remain.

For LEV professionals, this integrated approach closely reflects the philosophy of modern occupational hygiene and the principles promoted throughout LEVCentral.

Further Resources

Recommended Learning

Thought Leadership

Although relatively specialised, OCE9 contains lessons that extend well beyond the offshore industry.

The document demonstrates that good exposure control begins with understanding how contaminants are generated during the process. In this case, drilling muds release mists and vapours at predictable locations, allowing engineers to incorporate extraction and containment directly into the equipment design.

For LEV professionals, the guidance provides another excellent example of process-integrated ventilation. Rather than adding extraction as an afterthought, the engineering controls become part of the drilling system itself. This approach not only improves worker protection but also produces more reliable and sustainable exposure control.

From a LEVCentral perspective, OCE9 reinforces a recurring theme found throughout the best HSE guidance: successful occupational hygiene is achieved through multiple complementary engineering and management controls working together, with Local Exhaust Ventilation playing a central—but not isolated—role in protecting workers’ health.