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The ideal Safe System of Work (SSoW) at any location reduces the risk of performing that work to a level referred to as “As Low As Reasonably Possible” or ALARP in risk assessment terminology.
The most common method of achieving this lowest risk situation is the Permit to Work (PTW) system which is used globally in the Construction and Oil industries. Enablon (a risk management solutions provider) state that the PTW system should be designed to manage the risks associated with a particular task due to the conditions in a specific environment. Reducing the occurrences of hot work in favour of cold work would be a major benefit to any risk reduction strategy.
Types of permits used in explosive environments
They identify the four most commonly used types of permit as:
- Hot Work permit
- Cold Work permit
- Confined Space Entry permit
- Special permits which typically cover radioactive materials, dangerous chemicals, excavations or power isolations
The American Petroleum Institute defines hot work as any work that involves welding, burning, or hot tapping or the use of equipment near an open flame or equipment capable of generating a spark.
Cold work describes a situation where the task being performed does not generate any sources of ignition. Therefore, any activities such as grinding for surface preparation, cutting, drilling, or where work involves the use of standard pneumatic hammers and chippers requires a hot work permit if there is spark potential. This also includes the use of non-explosion proof electrical equipment such as lights, tools or heaters as they are all capable of internal spark generation.
The safety requirements for hot work to take place when compared with cold work are considerably more onerous. For example, Shell Oman (PDO) have additional restrictions for hot work if required in Zone 0 and Zone 1 areas where that type of work is normally prohibited, which can be summarised from their PTW system:
“If hot work cannot however be avoided and is essential the Responsible Supervisor must formally prove there is no other alternative practicable way of avoiding hot work before authorising it in these zones. He must also ensure the following:”
- The process system(s) which resulted in the area being classified as Zone 0 or 1 are shut down, isolated and de-pressurised so the hazard leading to the area classification as Zone 0 or Zone 1 is removed during the hot work.
- Continuous gas monitoring shall also be required.
- Watchmen shall be posted both inside and outside of the area.
The additional risk assessments, monitoring and fire watch personnel would not be required if the hot work could be performed by equally effective tools, known as Cold Work tools, which do not have spark potential.
Self-certifying of equipment by companies claiming that it would be safe to use in an explosive atmosphere for either the mining or petroleum industries would rightly be treated with skepticism. For this reason, TFT-Pneumatic has had stringent testing performed on their range of equipment by DNV GL, one of the world’s leading certification bodies, before classing any product as a Cold Work tool.
DNV GL Certifications
The certification awarded by DNV GL is based on their evaluation and testing of equipment for compliance with either ATEX or IECEx regulations depending on geographic requirements. ATEX standards, which are used in the EU, are regarded as better than or equivalent to the standards applied in the USA or Canada for explosive atmospheres. Only in Australia, India, New Zealand and Singapore do their governing industry bodies specify that IECEx certification is required. In those countries test reports used to qualify for ATEX certification would be acceptable as part of an application for IECEx certification as these standards are considered equivalent.
The use of Cold Work tools will lower operational risk by reducing the likelihood of any simultaneous operation or event, which might be uncontrolled, having a disastrous impact. Their cost-effectiveness can be difficult to quantify as the time spent raising a hot work permit in comparison to a cold work permit at any given work site is an estimate. However, an evaluation of the time spent raising permits in general was performed by Shell UAD for their Gulf of Mexico installations.
They estimated a range of time from 15 minutes to over 60 minutes per permit where a hot work permit is at the upper end of that range. We can assume that there is an increase in time spent raising a permit for hot work rather than for cold work due to gas testing and fire watch arrangements. Therefore, we can use their annual permit figures to see the potential time difference raising hot work instead of cold work permits.
The Shell case for change for their PTW system was based on the following facts and figures:
- Wait time and non-value-added permitting identified as offender in decreasing capacity of workforce
- UAD averages 24-26,000 permits annually with an average of 2500 monthly per month (does not include tasks that require only Job Safety Analysis)
- Average time to create (not copy) permit: 15- 60+ minutes
Although the scale of any organisation’s activities vary, it can be seen that additional time spent on hot work permit raising is effectively Non-Productive Time if a cold work permit could be used with superior equipment for a more cost-effective operation.
The following link demonstrates the use of a non-sparking angle grinder for a damaged oil tank repair at a refinery without resorting to a special habitat. Without cold work tools, this would be a higher-risk activity requiring a hot work permit.
HSSE World also supports the use of cold work tools in as many applications as possible, stating:
“All HSSE managers must look for the set of tools that deliver the right mix of performance, cost-effectiveness, and above all, safety.”
Benefits of using cold work tools
They summarise the benefits of using cold work tools as:
- No need for hot work permit – Certified by a third party as cold work tools
- No need for time-consuming risk evaluation – No risk as it is cold and safe work
- Avoids postponements – As the tool can be used safely, jobs do not have to be postponed
- No need for habitat – No chance of igniting gas or damaging nearby equipment
- No need for fireguard personnel – No ignitions
- Avoids production stop/delays – Potential to save a lot of money
References
- Enablon – Safetip #98: Use Different Types of Safe Work Permits. https://enablon.com/blog/safetip-98-use-different-types-of-safe-work-permits/
- American Petroleum Institute – Hot Work Permitting. https://www.api.org/oil-and-natural-gas/health-and-safety/worker-and-worksite-safety-resources/worker-safety-rules-to-live-by/hot-work-permitting#:~:text=Hot%20work%20is%20any%20work,a%20fire%2C%20explosion%20or%20release
- Shell, Petroleum Development Oman (PDO) – PR1172 – Permit To Work Procedure, Page 15 https://www.pdo.co.om/hsems/Documents/Procedures/PR-1172%20-%20Permit%20to%20Work%20Procedure.docx
- Shell Microsoft Powerpoint – DW3 Permit To Work matrix rollout. https://www.shellcontractor.com/pubdoc/fileaway/gomconstruct/forums/2014/march/DW3Permit_to_WorkMatrixRollOut.pdf
- HSSE World – What are Explosive work Environments and how to select the right tools.
