HSE webinar follow-up: UKCS process isolation Q&A

HSM recently hosted a webinar with the HSE focused on the use of process isolations within the UKCS offshore oil and gas sector. The session provided valuable insight into the relevant legal requirements, clarified regulatory expectations, and explored what constitutes good industry practice in order to drive continuous improvement in process isolation management.

The webinar generated significant engagement, with many thoughtful and important questions raised by attendees. Unfortunately, due to time constraints, we were unable to address all questions during the live session. Following the event, HSM liaised directly with the HSE to ensure the outstanding questions were reviewed and answered.

We are pleased to now share the responses, providing further clarity and supporting the industry in maintaining safe, compliant, and effective process isolation practices.

Are they any reflections you can share on what you see during inspections in relation specifically to when and how onshore SME engagement and requirements for approval should be framed and how that is managed across different company management systems?

In our experience, subject matter experts (typically Technical Authorities) set the isolation standards for the organisation. The responsibility for ensuring these standards are being followed at site lies with the OIM. Most company standards set out when onshore technical authorities should be engaged, such as when the isolation standards cannot be met or there is a requirement to deviate from these standards.

Figure 1 of HSG253 (responsibilities of key personnel) provides an overview of the responsibilities of key personnel involved with isolations and this is broadly inline with most organisations operating in the UKCS. 

It is important to clearly define roles and responsibilities for onshore SMEs within your isolation procedures. They should be used for authorisation of risk assessments for isolations that do not meet the baseline standard. This is sometimes carried out within the electronic safe systems of work, or can be achieved by recorded communication. SMEs should also be involved in monitoring and audit of isolations. From these activities they should consider plant modifications to reduce risk.

Where would one find HSE guidance on identification of line breaks? It is clear that all isolation  points (locked valves, bleeds, blanks etc) must be marked up on a P&ID but what would the HSE expect with regards to identification of line breaks. Thanks.

The most relevant guidance you are looking for would be the Energy Institute publication titled “Guidelines for management of integrity of bolted joints in pressurised systems”, the latest edition (3^rd edition) was published in October 2021. Section 6 of this guidance (records, data management and tagging) will help address your query.

Good practice would be to have all disturbed joints identified on P&IDs with the associated joint number clearly identified and allow easy correlation against flange break tag locations and the joint management system.

Is this as applicable to Drilling Contractors as Duty Holders as it is to Platform Operators?

Yes, Paragraph 3 of HSG253 outlines areas where this guidance applies and specifically describes that it has a general application to all industries where process isolations are made, and applies to mobiles offshore drilling units where relevant, such as for well testing. 

What is the HSE view where electrical isolation standard cannot be met, for example, a lockable fuse insert cannot be fitted, what is the expected justification or route to deem an alternative method ie. taping fuseways

Deviations from electrical isolation standards are expected to follow the same process / methodology for mechanical isolations.  In the first instance, the electrical isolation should be extended wherever possible such that the standard can be achieved.  If this is not possible then suitable alternatives should be explored and supported by appropriate risk assessment.  Taping of fuse-ways is not considered a suitable alternative when other methods are readily available.  

Reference should also be made to HSG 85 for additional guidance on safe working practices on electrical systems.

Some good points raised, I’m a big fan of HSG253 Is best practice still a checklist approach for isolations applied and locks listed that you are placing a personal board against?

Checklists can be useful depending on the situation. In our experience, most organisations have implemented electronic based safe systems of work which can be used to provide a range of overviews such as isolations in place and locked valves as you mention. 

If I am sending valve technicians to a customer’s site for remedial work or maintenance – what should they be looking for to ensure isolations have been successful and the area is safe?

Your valve technicians should be broadly familiar with the requirements of HSG253 so they will know if the isolation that has been applied is to the correct isolation standard for the service its being used for. As required by HSG253 (paragraph 173) you should also ensure that someone from site demonstrates to your technician that the there is no leakage and pressure within the isolation boundary before containment is broken. We would also encourage your technicians to challenge any isolation arrangements that they deem not to meet the isolation standard and request an inspection of isolation documentation, risk assessments and field check isolation valves if they need reassurance.

Curious on numbers, today we were presented with 6 examples.  How many cases are the HSE investigating per year of this nature?

Not all of the examples discussed during the webinar were related to an investigation or resulted in a hydrocarbon release however typically we have been seeing an average of 1-4 incidents involving some aspect of failures in isolation.

Our inspections are however routinely finding deficiencies in isolation practice offshore which do not reach the point of an incident but could result in a different outcome should the failings occur in the future.

OEUK work group along with Scott Templeton paid a visit to a training provider to review the SIRPS training course, was the training course deemed sufficient from the HSE perspective?

HSE do not comment on the suitability of training courses provided however we do expect that any training and competency assessment includes an appropriate level (number and complexity) of practical demonstration of all aspects of the isolation process.  This demonstration can be achieved either through dedicated training providers or through in-house arrangements at site.

Are you seeing operators reluctant to deem personnel as incompetent?

No. Most organisations have specific competencies related to isolations that individuals have to demonstrate to be deemed competent. 

We have not come across a situation where an individual applied an isolation that was not deemed as competent to do so within their own organisation. 

As a general observation, some organisations have ‘stricter’ requirements than others and we have found issues with the quality of some isolation training and assessment programmes.

It is also worth highlighting that many of the incidents we investigate or issues we find during inspections related to isolation failures involve individual errors made by individuals deemed as competent. 

How many times can you use a non standard isolation on a specific item before you need an engineering change

There is no defined limit on the use of non-standard isolation.  HSG253 states (paragraph 137) that you should consider improving the isolation design after each use of a non-standard isolation and at the first opportunity. However, it goes on (paragraph 138) to say that an ALARP type argument should be used in concluding whether a modification should be made. 

Our expectation is that organisations keep records of how many non-standard isolations they are applying and ensure that they are reviewed regularly, and engineering changes implemented where practicable to do so. Extending the isolation boundary or deferring the work to a shutdown window should always be considered in preference to a non-standard isolation.

What is the HSE’s opinion on adjusting isolations to a level 2 risk assessment if it involves the movement of a critically locked valve?

We have no concerns on moving critically locked valves as part of isolations, as long as these valve movements are tracked, locked valves registers kept up to date and those involved with the isolations clearly understand and assess the hazard created when the critical valve is moved and that the valve is returned to its ‘normal’ position when the isolation is removed.  Good practice would be for locked valve registers to clearly identify the hazard introduced by changing the valve position in order to help individuals assess the risks correctly.

At what frequency should i conduct valve integrity test for a LTI?

Valve integrity tests are conducted before an isolation is implemented, including for a Long Term Isolation. The decision and criteria to move it to long term is company specific. In general, when a positive isolation has been tested, there is no need to repeat the integrity test, but the isolation boundary does have to be monitored for pressure build up at an appropriate frequency. This needs to be determined by risk assessment considering the isolation design, such as if valved or positive, and conditions. The review should ensure the isolation in place remains as per the ICC and may need to be redesigned if pressure is detected within the boundary during the checks.

Should a LTI be required for use as part of a maintenance activity then a formal integrity test of the isolation should be conducted / repeated at that point.

It is a standard requirement in many procedures that all valves included in an isolation boundary undergo an integrity test, a measure I fully support. I have observed instances where valves were added during the completion of a Level 2 Risk Assessment by senior management, “because they want it,” without this crucial integrity testing, even when the isolation standard has been met.  Should these be proven?

Any valve used as part of an isolation must be integrity tested. Adding additional isolation points over and above what is required is always encouraged and these should be tested where possible to demonstrate they are an effective isolation valve. 

If they cannot be tested, they may still provide some benefit in preventing bulk transfer of hazardous substances but cannot be considered a proven isolation. A review of the defective valve or maintenance records should assist in determining if the valves are likely to form some barrier.

How does the HSE interpret compliance with HSG 253 for high-hazard, process-oriented industries outside offshore oil and gas—particularly for plants installed before 2006?

Compliance with HSG253 is mandatory for high hazard, process oriented high-hazard industries outside of offshore oil and gas including COMAN and non-COMAH industries where the release of a hazardous substance may occur when breaking containment. We do find issues with older assets complying with the required isolation standards due to their design, but HSG253 still applies and organisations should look to improve plant design where reasonably practicable to do so.  Any modifications made to older plant should ensure that modern isolation standards are adopted to ensure compliance with HSG 253.

Is there guidance for valve integrity leakage rates that are acceptable during testing? Based on line sizes and medium etc. I think integrity leakage rate criteria is lacking.

HSG253 does not provide specific guidance of acceptable leakage rates. Organisations should determine an acceptable leakage rate as it is situation / company specific based on the hazard presented by the fluid and the consequence of a release.

Paragraphs 180 – 183 of HSG253 provides some guidance for valve integrity testing. It’s important to highlight that any decision to carry intrusive maintenance with a known leakage is acceptable only if risk assessment demonstrates the residual risk to be tolerable. 

Is there a plan for a revision or update to HSG253?

There are no plans to revise or update HSG253 at this moment in time.

Use of the isolation selection tool for a typical high-pressure gas system, results in the baseline standard almost always being “positive isolation”. This in turn would require the same standard of isolation to allow it to be safely applied. This results in a Catch-22 situation. Is it fair to say that the risk assessment therefore needs to consider the exposure time & complexity in applying the positive isolation versus conducting just the task?

Yes, and we have seen organisations adopt this approach and implement a “time at risk” aspect to their isolations. For short duration work (e.g. <24 hours) if the isolation tool requires a positive to be installed, a proven double block and bleed isolation may be sufficient if risk assessment shows this to be acceptable. For category 1 fluids (very toxic etc.) this approach may not be suitable. It depends on the situation.  

HSG253 gives guidance on variations from positive isolation requirements for short-duration work in paragraphs 132 – 134.  This notes consideration of time needed to install and remove positive isolations as part of assessing risk, which may be reduced using a valved isolation if the activity duration is less than this. 

Are the new SIRP guidelines going to include details on reverse integrity gasket and witness joints requirements and use (and when not to use).

Plant reinstatement was not the focus of this webinar, but there will be something in our SIRP guidance about the use of reverse integrity gaskets and witness joints.

Reverse integrity testing (RIT) should only be used for joints which are not suitable for conventional leak testing. They do not provide the same level of assurance as a full internal leak test on the system because the joint is being tested in the reverse direction, so the forces and stresses are not the same.

RIT gaskets create a potential leak source from the test port. Any decisions to use these must be risk assessed and approved by relevant technical authorities and considered as part of the management of change process.

Existing guidance is available, particularly the Energy Institute “Guidance on safe plant reinstatement”,  1^st Edition.

What are the expectations from the HSE as regulator of independent verifier (ICP) involvement/review of isolations and management of this process? Noting typical Verification Schemes and Performance Standards are typically based around Specified Plant and less so Procedural and People factors.

The Independent Competent Person (ICP) has a set role in relation to verification and ensuring compliance with Performance Standards.  There is no expectation that they undertake verification activities related to the safe isolation of plant unless it forms part of any performance standard, e.g. locked open / locked closed valves.

The ICP is however expected to be consulted with regards any modifications to the plant and comment on the design suitability with regards recognised codes and standards which may include isolation design.

How does HSE expect organisations to demonstrate that their isolation controls are both effective and consistently applied, particularly in high-risk or multi-contractor environments?

All isolations should have an auditable paper trail demonstrating that the isolation was planned and implemented properly. When an isolation has been completed, the organisation should archive this information for a period of time. This information should be subject to suitable audit and monitoring which will demonstrate the isolation arrangements are effective and are consistently applied. Where issues are found, managed and recorded actions should be put in place to make improvements in a timely fashion. 

With regards to isolation design, how should different line sizes be considered?  For example, a 2” pipe is being replaced, but it is an off-take from a 6” line where the isolation valve is 6”. This can change the outcome to a DBB from SBB.  HSG253 consistently treats the isolation point as the valve or device that stops the hazardous energy source, not the reduced pipe size where work occurs, however in the typical examples page starting from page 65 of HSG253, most of the examples speak about the flange size which would support the argument of line size .

For the scenario you described, it would be the 6” line you would use for the selection tools. As you correctly point out it’s the point that stops the energy source. 

How can organisations ensure disposal routes for hydrocarbons are always safe and suitable?

Hydrocarbons should be routed to closed systems such as closed drains or flare headers where possible. The goal is to prevent unintentional releases to atmosphere where it may accumulate and create a risk.  Where disposal to atmosphere is considered, then the risk assessment should include engineering checks, such as by dispersion modelling, to evaluate the consequences as well as considering the situation. For example, if the release will be into a well-ventilated or normally safe area and what work activities are ongoing.

You can watch this webinar on demand by registering here.