SPC/Enforcement/141
To provide guidance to Inspectors on inspecting PE natural gas main and service installation standards and on enforcement policy.
1 The majority of new natural gas mains and service installations are PE and as the iron mains replacement progresses, over 3500 km of new mains are being laid annually, mainly by contractors to the gas distribution network operators.
2 Inspectors have found poor PE standards throughout the distribution networks. Usually these were dealt with on a case-by-case basis. The Unit ran a PE Gas Systems Integrity Seminar in August 2007 to improve understanding of the main areas of concern, ensure a consistent approach and explore enforcement policy.
3 The scope of this guidance is limited to requirements for ensuring the safety of the PE installation. It does not include occupational health and safety risks during installation, for example the risk from gas during the safe control of operations procedure nor other risks such as construction and manual handling risks.
4 The principal legislation governing PE installation standards are:
5 PSR Regulation 9 states that:
The operator shall ensure that no fluid is conveyed in a pipeline (save for the purpose of testing it) unless it has been so constructed and installed that, so far as is reasonably practicable, it is sound and fit for purpose for which it has been designed.
6 The duty is therefore on the operator (not the installation sub-contractor) and only applies when gas is conveyed. There is therefore no breach of PSR Regulation 9 at the time of installation.
7 The duty is ‘so far as is reasonably practicable’. HSE expects, as a minimum, that operators should comply with good practice guidance. In respect of PE installations standards, these are covered in well-established industry procedures. And they are designed to ensure the installation remains sound and fit for purpose for 50 years or so.
8 The safety case should contain sufficient particulars on technical specifications and arrangements sufficient to show PE systems are installed to standards necessary to comply with the requirements of PSR Regulation 9. This may be covered by reference to an Engineering Requirements Manual and/or the mains and service laying manuals.
9 The safety case should include arrangements for ensuring adequate standards are met, employee and/or contractor competence, and monitoring and auditing health and safety performance. Poor installation standards may indicate wider failings in the operator’s management system, particularly at supervisor level.
10 The conveyor has a duty to comply with the procedures and arrangements in the safety case.
11 An Inspection checklist is at Annex 1. A template is available to record findings if required.
12 The integrity of a pipe joint is affected significantly by its cleanliness, alignment and compliance with the correct fusion cycle. These failings are more serious on medium pressure systems where the risks are inherently greater than for low pressure systems.
13 Inspectors will need to make a judgement as to whether the failings seen would lead to a potentially unsafe installation. This may be because of a single failing or a combination of factors. For example, a clearly misaligned electrofusion joint or evidence of a failure in the fusion process (e.g. melt coming out of the fitting, concern with the joint indicators) would raise serious concerns about the joint integrity. But there may be a combination of factors which would raise similar concerns, for example failure to store fittings properly, evidence that alignment clamps have not been used, poor joint cleaning. As well as concern over the management of a specific installation, these failures may indicate failings in the wider management arrangements, particularly regarding supervision.
14 Enforcement decisions should be made within the framework of HSC enforcement policy and the Enforcement Management Model (EMM).
15 The paragraphs below discuss application of the EMM in helping Inspectors make consistent enforcement decisions. However, the EMM recognises it has limitations and cannot capture all the nuances and complexities of discretionary decision making in all circumstances. HID SPC/Enforcement /61 provides guidance on the use of the EMM in HID, including its application to permissioning regimes.
16 Inspectors should deal first with matters at a specific PE installation which, in their opinion, give rise to risk of serious personal injury. This could be as a result of a single failing (e.g. a misaligned joint) or combination of failings as described above. They should then consider how best to achieve sustained compliance with future PE installations. For this, Inspectors will need to consider two issues. Is the safety case good enough to control the risk? If it isn’t, the safety case will need to be revised. If the arrangements in the safety case appear satisfactory, then lack of compliance with the safety case will be the main issue. The enforcement options will vary depending on the situation found.
17 EMM section 2 deals with risk of serious personal injury.
18 The Enforcement Guide states that where there is a risk of serious personal injury, then the initial enforcement expectation is a Prohibition Notice (PN) rather than an Improvement Notice (IN). A PN applies to activities which are being or are likely to be carried on and which will involve a risk of serious personal injury. Personal injury includes any impairment of a person’s physical condition (HSWA S53).
19 Therefore, even if gas is not being conveyed at the time of the inspection, but you form the opinion that the installation would lead to risk of serious personal injury, then a Prohibition Notice (PN) can be served (Railtrack v Smallwood [2001] ICR 714). The risk need not be imminent (Tesco v Kippax and Railtrack v Smallwood). This is very relevant to PE installations where the safety factors are such that, for example, a poorly constructed joint could remain intact for a number of years. But, if the standards seen indicate that that the joint has a risk of failing within its expected lifetime, a PN remains appropriate.
20 The PN should be served on the operator of the pipeline as they are the person who will convey gas and create the risk. It should not be served on the installation contractor.
21 Section 5 of the EMM gives the option to vary the initial enforcement expectation (IEE - see below). Dutyholder factors are shown in the EMM in Table 6 and in flow charts 3 – 6. Flow chart 3 deals with the situation when a PN is the IEE. With a PN, there is no option to lower the IEE of a PN. Strategic factors can qualify this decision subject to management review but it is likely only to confirm the decision.
22 The operator may decide to remedy the situation before the PN is served.
23 As discussed, the PN will deal with the risk at a specific installation but Inspectors should consider whether they need to take further enforcement action to secure sustained compliance. Inspectors should therefore proceed through the EMM as below.
24 The GSMR safety case should define both the technical and managerial arrangements to ensure the PE installations are fit for purpose. Operators have a duty to comply with the arrangements set out in the safety case. Where standards seen indicate failure to comply with mains and service laying manuals in relation to controlling risks from the gas, or with associated management arrangements (e.g. ensuring suitable competence and supervision), then these should be addressed.
25 Risk gap analysis can be used to consider possible enforcement action where a duty holder has failed to adhere to conditions in the permissioning (safety case) document. The first step in the EMM is to determine the risk gap which compares the actual risk (where the operator is) against the benchmark (where the operator should be). Failure of a PE pipe could foreseeably lead to multiple off-site casualties and therefore risk Table 2.2 should be used.
26 In referring to Table 2.2, the benchmark where the duty holder should be is a nil/negligible risk of serious personal injury (in this case to members of the public). If the standards are right and adequate managements arrangements in place, a properly installed PE pipe should be safe (excepting third party damage incidents) for its expected lifetime of 50 years or more. A failure to comply with arrangements in the safety case (or if the arrangements described are inadequate in themselves) could lead to poor standards of future PE installations. There is then a risk, even though remote, of a leak which could lead to serious personal injury. Risk Table 2.2 would then put the risk gap at substantial.
27 Section 4 of the EMM deals with risk gap analysis as a guide to initial enforcement action (IEE). There are three tables covering IEE:
28 Table 5.3 is for use only with Explosives licences, Mines exemptions, Fire certification and COSHH exemptions. It should not be used for the GSMR regime.
29 Table 5.2 - Compliance and administrative arrangements is concerned with requirements which are not in themselves risk based e.g. safety case not submitted, failure to provide information required by permissioning regimes. This is unlikely to be relevant in this initiative.
30 Table 5.1 should therefore be used to determine the IEE.
31 The standard required for PE installations can be considered as ‘Established’ as they are set out in well-defined, industry wide documents (i.e. the mains and service laying manuals). With a risk gap of substantial, Table 5.1 then gives an IEE of an Improvement Notice.
32 Section 5 of the EMM considers the factors which may vary the IEE. Inspectors should consider firstly dutyholder factors and then strategic factors as to whether the IEE should be varied.
33 Figure 4 gives guidance on duty holder factors when the IEE is an Improvement Notice. With an intervention on this scale, then this chart should be used with caution as it is more relevant for factory type sites. For example, if we consider the ‘Inspection history’ decision gate, previous ‘poor’ history leads to prosecution. This may be appropriate with wide spread, long term failures in improving PE standards but this should not be used for isolated incidents where the conveyor is trying to improve standards. Indeed, at the early stages of this intervention, a letter with agreed improvement plan would be acceptable. An IN may be required if improvements are not made in time.
34 There are a range of strategic factors which may impact on the final enforcement decision (see EMM Table 7). Inspectors have to ensure the public interest and vulnerable groups are considered. The public would rightly expect a new gas network to be installed properly so that it is safe.
35 Because of the complexity of this initiative, there may be a need for management review to agree enforcement decisions.
36 The wording for a sample prohibition notice is at Annex 2.
For further information, contact HID Gas & Pipelines Unit SI3D.
| Documentation | Comments |
|---|---|
| Does the team have access to main and/or service laying manuals? | The manuals allow the teams to check on current procedures on site. It would be difficult for teams to demonstrate they are following procedures if they do not have the procedures readily available. |
| Pipe handling | Comments |
|---|---|
| Coil dispenser used? | Safety of employees/contractors. Minimises the risk of damage to the PE pipe. |
| Coil unbanding carried out in a controlled manner? | Safety of employees/contractors. Coils can spring out if released carelessly causing injury |
| Pipes and coils stacked correctly? | Safety of employees/contractors and public Prevents excessive pipe ovality |
| Electrofusion jointing | Comments |
|---|---|
| Are all fittings stored in bags ready for use? | Cleanliness of the fittings is essential to joint integrity. Contaminated fittings should be discarded. |
| Is there any evidence of damage on the pipe (10% rule)? | Damage where the joint is made potentially affects the joint integrity. Although current standards allow for a 10% loss to pipe damage, it is poor practice to lay damaged pipe regardless of percentage loss. |
| Is there evidence of proper scraping on the pipe to be jointed? | Preparation of the pipe is critical to joint integrity. NB Pipe scraping is not normally needed on the core pipe of peelable pipe unless it has become contaminated during skin removal in which case it is permissible to scrape it clean. |
| Are the pipe ends cut square? | Contributes to proper joint alignment. If the joint has already been made, this is difficult to check but it is a good question to ask how the pipe was cut. |
| Has the pipe exposure tool been used to remove skin on peelable pipe? | Failure to use a proper tool may damage the parent pipe. |
| Does the team have access to mains and/or service clamps for various sizes of pipe? And have they been used? | Use of clamps is important to ensure correct alignment and joint restraint during the fusion cycle. This is particularly important on larger diameter mains. A range of clamps for the pipes being installed should be available on the vans. |
| Does the team have access to mains and/or service clamps able to clamp bends? | As above. The team must have appropriate clamps for all electrofusion joints, including elbows and bends. |
| Is there evidence of marking on the pipe to assist in aligning the pipe into the socket? | If there are no markings evident, it is difficult for the teams to demonstrate correct alignment or ensure that the assembly has not moved during the fusion cycle. |
| Is there any evidence of misalignment? | Serious misalignment is unacceptable. |
| Has the correct electro fusing time been allowed? | This ensures quality of the joint. If clamps have not been used to restrain the joint for the duration of the heating and cooling cycle, the joint could be weakened |
| For tees, has the correct loading tool been used? | Correct loading is necessary to ensure the tee/pipe joint is made properly. Too much pressure can result in weld being expelled from the joint, too little pressure results in a poor weld. |
| Correct cooling time been allowed before the clamp is removed? | This ensures the quality of the joint. If clamps have not been used, they can’t demonstrate this. The team should be aware of the appropriate cooling time. |
| Have the joint indicators risen evenly? | The pop-up indicators show whether weld melt pressures were generated. In themselves they are not reliable in determining the quality of the joint. However, if the indicators have not risen evenly, then the quality of the joint may be poor. |
| Is there any evidence of melt that has come out of the fitting? | Indicates possible misalignment and potentially a poor fusion joint. |
| Are the proximity distances between fittings correct? | The failure to comply with proximity distances does not necessarily affect the integrity of the joint. But it shows non-compliance with procedures and may indicate clamps have not been used. |
| Are services laid at shortest length SFAIRP? | The design, construction and installation of gas service pipes, Approved Code of Practice and guidance, L81, paragraph 11, requires the service pipe to be designed ‘ …. in such a way that it is least likely to be affected by third party interference or subject to accidental damage’. The guidance in paragraph 16 states that ‘the route should be the shortest route possible, SFAIRP. This is also a requirement within the Distribution Network Operators’ Service Laying Manuals. There has been evidence of poor practice in industry of excavating a small hole and then squeezing in as many service connections as is possible, resulting in confused and congested services pipe runs. It can result in several service pipes running parallel to the main, increasing the risk of third party damage. The practice often requires several joints and elbows within a short distance to align the services to the main. A larger excavation allows greater flexibility to align the service directly on to the service tee. Wherever practicable the line of the service should be at right angles to the main but may require diversions to accommodate any obstructions. |
| Are pipes laid at the recommended depth? | Service pipes should normally be laid at a minimum depth of 375 mm in private ground and 450 mm in footpaths and highways. Mains should normally be laid with a minimum depth of cover of 750 mm in a road or verge and 600 mm in a footpath. Where a lesser depth is required, additional protection against third party damage should have been considered. |
| Are squeeze off points far enough away from other fittings? | Squeeze offs too close can damage existing joints. Following a serious fire resulting from a butt fusion joint failure in 2008, DNOs have adopted various precautionary approaches to flowstopping near to joints of suspect quality. |
| Has the pipe been checked for longitudinal scoring prior to squeeze off | Scores in the squeeze off area act as stress raisers and could be initiation points for rupture. |
| Has the skin been removed from peelable pipe prior to squeeze off? | This is mandatory for peelable pipe. |
| Have squeeze offs been re-rounded? | Removes stress within the pipe. |
| Is there a re-rounding tool available (sometimes same tool as a mains clamp)? | As above. |
| Have squeeze offs been correctly taped? | Additional squeeze off operations can affect pipe integrity so it is vital that tape is applied to prevent squeeze off occurring more than once in the same location |
| Butt fusion joints | Comments |
|---|---|
| Was the first weld off the day, cut out and discarded? | Ensures plates are clean. For larger diameter pipes, often two welds are discarded. |
| Is the hot plate clean and smooth? | Ensures joint cleanliness. |
| Is the trimmer sharp and free of debris? | Preparation of joint face important for strong joints |
| Have joints been left in fusion machine until the end of the fusion cycle? | Ensures quality of the joint. Disturbing the joint before it has cooled sufficiently will weaken it. |
| Are there any precautions taking to protect against adverse weather, e.g. a shelter, end caps to prevent wind chill? | Ensures quality of the joint. Excessive cooling prior to butting pipe ends together or dust contamination will weaken the joint. |
| Pipe roller supports used? | Lessens risk of pipe damage or misalignment, reduces manual handling risks. |
| Have beads been removed with an approved bead removal tool? | The geometry of the beads is used to check the quality of the butt fusion and a proper tool should be used. |
| Have bead widths been measured using a bead gauge? | Confirms joint made properly. Teams should also be twisting and bending the beads and checking for cracking and contaminants at the interface as part of standard quality checks. |
| Have beads been numbered and retained? | Audit arrangements. |
| Has bead checks been retained in a “project file”? | Audit arrangements. |
….. hereby give you notice that I am of the opinion that the following activities namely:
The conveying of natural gas in a polyethylene pipeline
which are being carried on by you/likely to be carried on by you at:
Location/network address/place of activity
involve/will involve, a risk of serious personal injury, and that the matters which give rise/will give rise to the said risks are:
[summarise the failings seen in the installation standard] such that there is a risk that the pipeline will fail, release natural gas and expose people, including members of the public, to a risk of fire and explosion
and that the said matters involve/will involve contravention of the following statutory provisions:
Pipelines Safety Regulations 1996, regulation 9
Because
the pipeline has not been constructed and installed that, so far as is reasonably practicable, it is sound and fit for purpose for which it has been designed
and I hereby direct that the said activities shall not be carried on by you or under your control immediately/after [date] unless the said contraventions and matters have been remedied.
Add schedule if appropriate
