SUE Survey Safety Refinery Checklist: Permits and Zones

Why is SUE survey safety in a refinery different from a road job?

Because the ground you scan sits inside a plant where one spark, a dropped tool or an unplanned excavation can start a chain of events that no one can stop. Flammable vapour, pressurised lines and hot surfaces join the usual road risks, and no square metre is touched without the unit in-charge's signature.

That changes how a subsurface utility engineering (SUE) job is planned. Ground penetrating radar times how long each pulse takes to bounce back from a buried pipe or cable, and that does not change inside the fence. The order of work does: documents first, permits second, gas test third, scan fourth.

Which permits does a GPR crew need inside a refinery?

A cold work permit for scanning, a hot work or equivalent clearance where non-certified electronics enter a classified zone, and a separate excavation permit for any trial pit. Indian oil and gas plants run a permit-to-work system based on OISD-STD-105, the work permit standard of the Oil Industry Safety Directorate, and each plant keeps its own version.

• Cold work permit: covers non-intrusive work with no ignition source, such as a walk-over scan in a non-hazardous area.
• Hot work permit or equipment clearance: most GPR units, locators and laptops are not certified for a classified zone. The plant treats them as a possible ignition source and names each device on the permit.
• Excavation permit: a permit to work excavation clearance covers any trial pit or vacuum excavation that confirms a mark. The area in-charge issues it only after reviewing the scan results.

What should the crew carry before entering the gate?

A complete document pack, the right protective equipment and a list of every powered device, checked against plant rules before mobilisation day. We send the pack to the client's safety officer at least two working days before the first site day.

The pack holds a crew list with ID proof and medical certificates, a method statement and a job safety analysis in the plant's JSA or HIRA format. A device list with battery types lets the safety team decide which zones each item may enter. Induction takes about half a day, and scanning seldom starts on the first morning.

What lies under a refinery, and what tends to go wrong?

A dense mix of firewater mains, oily water sewers, earthing grids, cathodic protection cables, instrument cables, buried process lines and storm drains. These underground utilities grew over decades of revamps, so existing records seldom match the ground. Surface features such as valve chambers give clues, not the full picture.

• Firewater ring main: often the largest buried pipe in a unit. A strike here can disable fire protection for the whole block.
• Oily water sewer: old joints leak, and the fluid washes fine soil away, leaving soft spots and cavities under paving.

Where leaks have run for years, add a cavity check before cranes or heavy vehicles use the area. Our void detection details explain how GPR picks up loose fill and air gaps under slabs and roads.

How does the crew work in a classified zone?

A hot zone survey runs in short permit windows, each opened with a fresh gas test. An area operator can stop the work at any time, and two habits keep the crew safe:

• Batteries are changed and charged only in the non-hazardous area, never inside a unit.
• If the gas alarm sounds, the crew switches off, leaves the trolley in place and walks to the assembly point.

Refinery SUE checklist at a glance

Seven items decide whether a crew scans on day one or waits at the gate; the table shows who owns each one and when it is due.

Inside the fence the refinery owns most of what is buried, so outside alert systems rarely apply there. For pipeline corridors and roads beyond the boundary, read about Call Before You Dig in India.

How sure is a GPR mark inside a plant?

A GPR or locator mark gives position and approximate depth; only a hand-dug or vacuum-excavated trial pit confirms the line beyond doubt. In SUE terms, scanning gives Quality Level B and a trial pit gives Quality Level A. Plants planning a new foundation or pipe rack footing often ask for QL-A at every crossing to reduce risks before piling.

Oil-soaked or saline soil, dense reinforced paving and repeating earthing grids all cut GPR depth and clarity. Our crews mark each line with a confidence level, so the plant knows which marks need a pit first. That step prevents accidental utility strikes and the service disruptions that follow them.

What should the final deliverable show?

A layered CAD drawing tied to the plant grid, showing each service with its depth, confidence level and the permit reference of the survey day. We follow the plant's layer names and colour code where one exists. The pack adds a PDF copy, a point list with coordinates and radargram snapshots for doubtful crossings. These utility maps then feed civil engineering design for the next revamp. For a fuller explanation of each item, read our note about GPR survey deliverables.

Plants planning a full-site campaign, not a single area, can see how our SUE survey for refinery works from first walk-down to final GIS layer.

What does a refinery survey cost?

Our GPR rate is ₹24 per metre for standard scanning and ₹32 per metre where an L-section drawing is needed, GST extra. The minimum order is ₹50,000 in Delhi NCR and ₹1,00,000 elsewhere in India. Permit windows slow refinery work compared with road work. The engineer therefore reviews the plot plan and permit system before confirming the schedule in writing.

Share your plot plan and the areas you want covered, and we will check rates for your site and send a written quotation.

Frequently asked questions

Can GPR equipment be used in a Zone 1 area?

Most GPR units are not certified for hazardous zones. The plant allows them only after a gas test, under a permit that names the device.

Who issues the work permit for a survey crew?

The area in-charge of the unit, following the refinery's own permit procedure. The safety department gives induction and gate passes, but the area owner signs the permit.

Does the crew dig trial pits as well?

Only when the scope includes it and an excavation permit is issued. Many refineries use their own maintenance contractor to dig, with our engineer present to confirm each mark.

How many metres can be scanned in a refinery shift?

That depends on the permit windows. A few hundred metres a day is typical inside a process unit; tank farm roads go faster.

Will the earthing grid hide deeper pipes?

It can. We scan in two directions and add electromagnetic tracing so the grid does not mask larger lines below. To understand how radar responds to buried metal, see GPR scanning.

Do you share radargrams and photos with the plant?

Yes. Photos follow the plant's camera rules, and the report includes radargram snapshots for doubtful crossings.

Written by Saniya Parveen · Technically reviewed by Rahul Rai · Updated 8 November 2026