Permit types on oil and gas sites

HSE-221 explained how a site decides which work needs a permit and described the common permit types and linked certificates found in most industries. Oil and gas sites use the same basic families, but the hazards inside the equipment, the hazardous area classification of most process areas and the presence of live wells and pipelines add some permit types, change the triggers for others and make linked certificates especially important. This lesson maps the work done on batteries, compressor stations, gas plants, well pads and pipelines to the permits that control it.

Routine work and permitted work

Not every task needs a permit. Operators taking readings, adjusting a choke within limits, changing a chart, sampling from a dedicated sample point or carrying out a written operating procedure such as pigging or a routine well shut-in are normally working under operating procedures rather than permits. The permit system is for work outside normal operation: maintenance, construction, inspection, cleaning, modification and any task that breaks containment, introduces an ignition source, defeats a safety system or puts a person inside equipment. Each company's permit standard should list which tasks are routine and which need a permit, and when in doubt the default should be to issue one.

Two features of oil and gas sites push more work into the permit system than in many other industries. First, most process areas are classified as hazardous locations because flammable gas or vapour may be present, so anything that could ignite it, from a grinder to a vehicle to a non-rated phone, needs control. Second, much of the equipment is sour or pressurized, so even minor maintenance can break containment.

The main permit types

Hot work in classified areas

Oil and gas companies usually divide hot work into spark-producing and open-flame work because the controls differ. Both need a gas test and a fire watch, but open-flame work also needs continuous gas monitoring, a larger clear zone, isolation or covering of nearby drains, vents and openings, and often a higher level of issuer. Lesson 5 covers hot work and gas testing in detail.

Many oil and gas permit standards treat anything that could ignite a flammable atmosphere in a classified area as hot work, even if nobody would call it that in a workshop. Examples include vehicles and mobile equipment with ignition sources entering a classified area, portable generators and compressors, non-rated cameras, phones and radios, battery-powered tools, and test equipment. Some companies issue a separate vehicle entry permit for classified areas, with a gas test at the point of entry and a requirement for the engine to be shut down if gas is detected.

Line opening and its relationship to isolation

The line opening or line break permit is the workhorse of oil and gas maintenance. It authorizes breaking containment on equipment that has held hydrocarbons, sour gas, produced water, chemicals or pressure. It does not stand alone: it depends on an isolation certificate showing how the equipment was isolated, a record that it was depressured, drained and purged, and a gas test at the break point. Lesson 6 covers line opening and vessel entry, and Lessons 8 and 9 cover isolation planning.

Wells, pipelines and other special cases

Some work does not fit neatly into the standard families.

• Wellhead and well work. Changing a valve on a wellhead, replacing a pressure gauge on the casing, or rigging up wireline or coiled tubing involves well pressure that cannot be isolated by closing a valve at a compressor. Companies usually control this work through well servicing procedures and the bridging document with the service contractor, plus a permit from the operator for the producing site, with barriers on the well confirmed before work starts. HSE-331 covered well servicing hazards.
• Pipeline work. Work on or near a pipeline right-of-way needs ground disturbance permits, crossing or proximity agreements and, for work on the line itself, isolation by valves, pigs or stopple fittings that may be kilometres apart. Hot taps on live lines are a specialized activity covered by their own procedures. HSE-332 covered right-of-way and pipeline hazards.
• Safety system overrides. Inhibiting a gas detector, bypassing a shutdown switch or jumpering a trip removes a layer of protection. Most companies require a separate override certificate, approved at a higher level, listing compensating measures and a time limit, and linked to the permit for the work that needs it.
• Work on a rig or frac fleet. Work on the contractor's own equipment is often under the contractor's permit system, as set out in the bridging document, while any connection to the operator's producing equipment comes back under the operator's system.

Building a permit package

Most real jobs need more than one permit or certificate. The program below takes a short list of jobs planned at the Spruce Ridge plant, described by simple yes or no features, and works out the permits and linked documents each one needs, following rules like those in the table above. It is the same logic a planner follows mentally, written down so that nothing is forgotten.

# Build permit packages for planned jobs from simple job features (teaching rules).
def package(job):
    permits, docs = [], []
    if job["opens_containment"]:
        permits.append("line opening")
        docs += ["isolation certificate", "depressure and purge record", "gas test record"]
    if job["entry"]:
        permits.append("confined space entry")
        docs += ["entry certificate", "rescue plan", "isolation certificate", "gas test record"]
    if job["flame"]:
        permits.append("hot work (open flame)")
        docs += ["gas test record", "fire watch"]
    elif job["sparks"]:
        permits.append("hot work (spark-producing)")
        docs += ["gas test record", "fire watch"]
    if job["override"]:
        docs.append("override certificate")
    if job["dig"]:
        permits.append("ground disturbance")
        docs.append("locate records")
    if not permits:
        permits.append("cold work")
    return permits, sorted(set(docs))

jobs = {
    "change amine filter element": dict(opens_containment=True, entry=False, flame=False, sparks=False, override=False, dig=False),
    "inspect inlet separator inside": dict(opens_containment=True, entry=True, flame=False, sparks=False, override=False, dig=False),
    "weld bracket on flare knockout": dict(opens_containment=False, entry=False, flame=True, sparks=False, override=True, dig=False),
    "replace gas detector head": dict(opens_containment=False, entry=False, flame=False, sparks=True, override=True, dig=False),
    "repaint pipe rack": dict(opens_containment=False, entry=False, flame=False, sparks=False, override=False, dig=False),
    "dig to expose drain line": dict(opens_containment=False, entry=False, flame=False, sparks=False, override=False, dig=True),
}
for name, features in jobs.items():
    permits, docs = package(features)
    print(f"{name}")
    print(f"   permits: {', '.join(permits)}")
    if docs:
        print(f"   linked:  {', '.join(docs)}")

change amine filter element
   permits: line opening
   linked:  depressure and purge record, gas test record, isolation certificate
inspect inlet separator inside
   permits: line opening, confined space entry
   linked:  depressure and purge record, entry certificate, gas test record, isolation certificate, rescue plan
weld bracket on flare knockout
   permits: hot work (open flame)
   linked:  fire watch, gas test record, override certificate
replace gas detector head
   permits: hot work (spark-producing)
   linked:  fire watch, gas test record, override certificate
repaint pipe rack
   permits: cold work
dig to expose drain line
   permits: ground disturbance
   linked:  locate records

The output shows how quickly the paperwork for one job grows. The internal inspection of the inlet separator needs a line opening permit and a confined space entry permit, plus an isolation certificate, a depressure and purge record, an entry certificate, a rescue plan and a gas test record. The welding job on the flare knockout drum needs an override certificate because a gas detector or flame detector nearby will have to be inhibited, or it will trip the plant when the welding starts. Replacing a gas detector head needs an override too, because the detector is out of service while it is changed, and the planner must decide what replaces it in the meantime, such as a portable area monitor.

One permit or several?

Companies differ on whether each activity gets its own permit or one permit covers a whole job with several sections. Separate permits make each hazard visible and allow different issuers to sign for different parts, but they multiply the paperwork and create more chances for permits to be filed apart, which was one of the failures at Piper Alpha. A single permit with sections is easier to manage but can hide a high-hazard step inside a long form. Either approach can work if every permit and certificate carries cross-references, the issuer reviews them together at the worksite, and the permit for the job cannot close until every linked certificate is closed.

Permit levels and issuer authority

Many oil and gas companies grade permits by risk, with higher-risk work requiring a more senior issuer, a second signature or approval from a supervisor or plant manager. Typical higher-risk categories are open-flame hot work in a process area, confined space entry, line opening in sour service, safety system overrides lasting more than one shift, and any work during start-up or shutdown. Grading keeps routine work moving while making sure that the most dangerous work gets the most attention. The grading should be written down so that issuers do not have to decide case by case under pressure.