Refinery Process Unit Demolition: The Contents Are the Job

A refinery process unit is a demolition job where the structure is almost irrelevant and the contents are everything. Columns, vessels, heaters, exchangers and kilometres of pipe have carried hydrocarbons, acids, catalysts and amines for decades. Some of what is left inside will ignite when it meets air. Some of it is toxic at very low concentrations. The steel itself is straightforward once it is clean, and getting it clean is the work.

This is how we approach refinery and petrochemical process unit demolition, what will hurt you, and what owners should have in place before anyone prices it.

What you are actually dealing with

• Columns, drums and vessels with hydrocarbon residue, sludge and scale. Pyrophoric iron sulphide scale in sour service equipment ignites on contact with air when it dries out.
• Fired heaters and furnaces with refractory lining, often containing refractory ceramic fibre and in older units asbestos, and burners on their own fuel gas system.
• Heat exchangers full of product and shell side fluids, and air coolers with their fin fan drives.
• Catalyst in reactors: spent catalyst can be self heating, can carry nickel, vanadium, arsenic or sulphur, and is regulated waste.
• Benzene, hydrogen sulphide, mercury (in gas plants), lead (in older fuel systems), amines and caustic in treating units, and hydrofluoric or sulphuric acid in alkylation units.
• Pipe racks carrying live lines from units that keep running, through the unit you are removing.
• Asbestos in insulation, gaskets and fireproofing, and lead paint on structural steel and vessels.
• The ground: hydrocarbon affected soil and groundwater under most of the footprint, with free product under some units.

Step one: the owner's decommissioning comes first

A refinery unit is handed to the demolition contractor only after the owner has shut it down, depressurised, drained, purged and steamed it out, and isolated it from the rest of the plant with positive isolation (spades or spool removal), not just closed valves. The handover documents matter: isolation register, gas test records, residual inventory, what could not be cleaned in place. Where the owner has not done this, it becomes the first stage of our scope and is priced as such.

Step two: characterise what is left

Residue sampling in every vessel, column and exchanger. Pyrophoric risk assessment on sour service equipment. Catalyst inventory and classification. Hazardous materials survey for asbestos, RCF and lead paint. Soil and groundwater investigation under the unit. The outcome of this stage decides whether equipment is cleaned in place, cut cold, or removed intact to a facility that can deal with it.

Step three: isolate live services through the unit

Pipe racks are the problem. Live lines from the rest of the refinery often pass through the unit being demolished. They are identified, protected or rerouted with the owner before any work starts near them, with the permit to work system controlling every lift and cut within reach of them.

Step four: make equipment safe for cutting

Vessels are opened under controlled conditions, gas tested, kept wet where pyrophoric scale is possible, and cleaned or inerted before cutting. Catalyst is unloaded under its own procedure and containerised for disposal. Refractory is removed and classified. Asbestos and RCF come out under the asbestos licence. Where equipment cannot be made safe for hot work, it is cold cut or removed intact.

Step five: dismantle and demolish

Exchangers, pumps and small vessels are disconnected and craned out whole. Columns and large vessels are lifted intact where the crane access allows, because cutting them in place is slower and riskier; where it does not, they are cut in engineered sections with the vessel supported throughout. Pipe racks are cut back in sequence once the live lines are protected. Structural steel comes down with high reach excavators and shears last, with lead paint controls on the cutting.

Step six: the ground

Under a process unit the ground carries hydrocarbons, and under some units metals and acids as well. Remediation is scoped from the investigation and run as a staged excavate, classify and treat or dispose program, often with groundwater recovery of free product. Clean concrete from foundations is crushed for reuse; contaminated concrete is not.

What not to do

• Do not accept a unit as decommissioned on a closed valve. Positive isolation or it is not isolated.
• Do not let sour service equipment dry out before it is opened. Pyrophoric scale ignites.
• Do not cut near a pipe rack until every line in it has been identified with the owner.
• Do not handle catalyst as rubble. It is regulated waste and can self heat.
• Do not hot cut coated or insulated steel until the asbestos, RCF and lead have been dealt with.

Approvals and notifications

Major hazard facility obligations stay with the owner and shape everything. Licensed demolition notification to the state regulator for structures and chemical installations, licensed asbestos removal notification, hazardous waste tracking for catalyst, sludge and residues, EPA involvement for contaminated land and groundwater, and the plant's own permit to work and management of change systems for every activity on site.

Who should be doing this

A contractor that has worked inside operating hydrocarbon plants under a permit system, owns its high reach and remote controlled plant, holds the Class A asbestos, demolition and waste transport licences in its own name, and runs remediation as a core service. Perfect Contracting carries out refinery, petrochemical and industrial plant demolition across Australia from its Sydney and Brisbane bases and travels for the right project. Read more about our plant decommissioning, oil and gas and site remediation work, or send us the details.