Safeguarding COMAH Sites: Best Practice for Storage Tank Integrity Management

Some of our clients with COMAH sites often get challenged on how they demonstrate the physical integrity of the plant and equipment.

This becomes even more challenging for old equipment or used equipment procured without CE marking, ATEX certification, material certificates, applicable design standards, records of operating and design conditions (pressure, temperature), inspection records and risk assessments etc.

As per guidance note #146 on the “Control of Major Accident Hazard (COMAH)” Regulations 2015, the physical integrity of plant and equipment must be considered at all stages from design through construction to operation and maintenance.

Case Study

Distilleries with bulk storage vessels containing high-strength alcohol are classified as dangerous substances due to low flashpoint and flammable nature. Some of the in-service vessels don’t have design information available which can make it difficult to justify their physical integrity during audits.

As per Scottish Whisky Association’s (3rd Edition) Purple Book, the design and construction of these vessels should be done to a recognised standard. The provision of adequate venting is very important both for normal operations and for the relief of excess pressure if the tank is involved in a fire. The design of venting arrangements should meet the requirements of a suitable standard such as BS EN ISO 28300: Venting Atmospheric and Low-Pressure Storage Tanks 44 or NFPA 30: Flammable and Combustible Liquids Code. The vents should be sized to take into account the pressure and vacuum rating, air rousing, pumping, and climatic breathing rates, and fire venting rate.

Depending on the process conditions, the vent needs to be adequately sized for the worst-case scenario. With the lack of actual design conditions, vent sizes can be deemed undersized which can require significant modification cost.

How can Integro Design Engineering Associates (IDEA) Ltd. support your site with integrity management?

• Through site survey our engineers and designers obtain key dimensional parameters and produce a general arrangement drawing and thickness profile.
• We establish the design pressure of vessels based on dimensional parameters with certain assumptions to carry out code (PD5500, ASME Sec VIII 1/2) compliant desktop analysis.
• The design pressure along with the fluid properties, operating conditions are used to carry out vent sizing calculations to a recognised code to ensure storage tanks are not over pressurised.
• Risk assessments to identify any further actions depending on the criticality.

EEMUA based inspections can also be organised via third party.

Get in touch with our Technical Director, Abhishek Bhatia CEng MIMechE for further guidance.

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