Fluid-filled systems · Georgia
We buy HPFF pipe-type cable system
Three paper-insulated cables inside a steel pipe, held under fluid pressure and terminated in porcelain potheads. HPFF is a system, not a reel, and it is bought as one — pipe, cable, potheads and pressurizing plant together.
- Steel pipe and cable
- Fluid pressure
- Potheads
01Overview
What this page covers
High-pressure fluid-filled cable was the way to put transmission underground before extruded insulation was trusted at high voltage. Three paper-insulated, lead-sheathed cables are pulled into a coated steel pipe, the pipe is filled with dielectric fluid and held at pressure, and the ends are made off in potheads. Routes at 69 kV through 345 kV were built this way in American cities.
What that means for a seller is that the material is not a reel. It is a length of steel pipe with three cables inside it, a set of potheads, stop joints, a pressurizing plant and a cathodic protection system. The cable itself is paper-insulated and lead-sheathed, so its recovery follows the same rules as any paper cable once the pipe is open. Removal is a decommissioning job before it is a sale.
02Specification
What an HPFF system contains
- System
- Three paper cables drawn into a coated steel pipe, 5 in. to 8 in.
- Voltage
- 69 kV through 345 kV
- Pressure
- Maintained at roughly 200 psi by a pressurizing plant
- Fluid
- Polybutene or alkylbenzene dielectric fluid
- Cable
- Paper-insulated, lead-sheathed, copper conductor
- Terminations
- Porcelain potheads, oil-filled; stop joints and sectionalizing joints
- Pipe
- Welded steel, coated and wrapped, cathodically protected
- Condition
- In service, decommissioned and drained, fluid-retained, abandoned
Ask whether the system was drained and purged, and by whom. A pipe that still holds fluid is a different job with a different cost before any metal is recovered.
03What we buy from a pipe-type route
What we buy from a pipe-type route
Drained and purged systems
The workable case: fluid removed, pipe purged, potheads opened and cable exposed. Pipe, cable, copper and lead are each recovered, and the section lengths are known from the route drawings.
Steel pipe as pipe
Coated transmission pipe in sound condition is reviewed on diameter, wall, coating and straight lengths. Pipe that has been cut into short pieces for removal is reviewed on weight.
Potheads and stop joints
Porcelain potheads, oil-filled, with their hardware and grading assemblies. They are counted, and porcelain that has been outdoors for decades is handled as fragile rather than as stock.
The pressurizing plant and controls
Pumps, tanks, gauges and alarms that held the system at pressure. They are part of the lot and part of the decommissioning, because the system cannot be opened until the pressure is off.
04Evaluation
How an HPFF lot is reviewed
The first question is the state of the system, not the state of the metal. Drained and purged is one review; still holding fluid is another; abandoned with unknown pressure is a third, and that one is not touched until the owner has proved the condition. Ask for the decommissioning record before discussing footage.
Then the pipe. Diameter, wall thickness, coating condition and the number of straight sections that can be lifted whole decide whether it is pipe or scrap. A coated pipe that has been in the ground for forty years is judged at the coating holidays, and a holiday is where the corrosion started.
Cable and accessories last, because they are inside the pipe. Footage follows the pipe length, so it is known before the cable is seen. Pothead count, copper size and lead sheath weight are recorded from the drawings, and the actual recovery is checked against them.
An HPFF system is a pressure vessel with a hydrocarbon inside it. Opening a pipe that is still pressurized releases fluid and gas at force, and the fluid is a skin and eye irritant that also has to be disposed of as a regulated waste. Nitrogen used for purging is an asphyxiant in a vault. Nothing is opened until the pressure is proved off, the fluid is contained and the vault has been tested for atmosphere.
05Seller terms
Before you sell: how it works
Four things a seller should be able to pin down before a truck is booked.
Verification
Footage is checked against the reel tag, the sequential marks on the jacket, the wrap count against the barrel, or a published weight per 1,000 ft — whichever the reel actually supports.
Payment
Payment method and timing are agreed in writing for the specific lot before anything is loaded or moved. No verbal number is treated as an agreement.
Paperwork
A bill of sale for the lot, and for utility material the owning utility’s release reference. Neither is optional and neither is created after the fact.
Freight
Collection is arranged as part of the terms. Say what can lift the reels and whether a 53-foot trailer can reach them, and the pickup is planned around that.
Sending a reel list and photographs costs nothing. A review is not a purchase, and nothing is bought, moved or scheduled until written lot terms are agreed for that material. Request a pickup when the lot is ready.
06Related
07Questions
HPFF pipe-type cable questions
Is the cable inside the pipe worth recovering?
Yes, as copper and lead. It is paper-insulated and lead-sheathed, so the recovery is the same as any PILC lot once the pipe is open and the cable is out.
Does the pipe have value as pipe?
Where sections come out straight and the coating is sound, yes. Cut sections and corroded lengths are reviewed as steel weight.
Who drains the fluid?
The system owner or its contractor, under the owner's environmental procedure. Fluid handling is part of decommissioning and is settled before a lot is moved.
Can an abandoned HPFF route be bought in place?
Only with the owner's records and a decommissioning plan. A route of unknown pressure and unknown fluid is a liability rather than a lot.
Send the route drawings and the decommissioning status
Pipe diameter, wall, section lengths and whether the system is drained govern the review. Pothead and stop joint counts follow from the drawings.