How to use a hydraulic pipe bender
Updated: 23 October 2026
The frame is on the floor, the pump handle is in your hand, and the amazon.co.uk box for a budget ram often contains no instruction sheet. You still need a sequence you can stand at the machine and follow. How to use a hydraulic pipe bender, for this class of manual ram, comes from what Clarke and Sealey print for their own 12 tonne machines, not from a KATSU manual we do not have. Match the die, centre the pipe, keep your hands clear, and stop if the wall collapses or the job is gas. The models in our [pipe bending machine comparison](/hub/diy-supplies/pipe-bending-machine) illustrate the hardware. Peter F. used those manuals, a UK hire leaflet and the listings, read on 22 October 2026. We did not run the pump in a lab. Links to amazon.co.uk can earn a commission at no extra cost to you.
The frame is on the floor, the pump handle is in your hand, and the amazon.co.uk box for a budget ram often contains no instruction sheet. You still need a sequence you can stand at the machine and follow.
The frame is on the floor, the pump handle is in your hand, and the amazon.co.uk box for a budget ram often contains no instruction sheet. You still need a sequence you can stand at the machine and follow. How to use a hydraulic pipe bender, for this class of manual ram, comes from what Clarke and Sealey print for their own 12 tonne machines, not from a KATSU manual we do not have. Match the die, centre the pipe, keep your hands clear, and stop if the wall collapses or the job is gas. The models in our pipe bending machine comparison illustrate the hardware. Peter F. used those manuals, a UK hire leaflet and the listings, read on 22 October 2026. We did not run the pump in a lab. Links to amazon.co.uk can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Drive | Bender type | Stated wall | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  WINMAX TOOLS AUTOMOTIVE WINMAX manual tube bender, 1 in to 3 in | Hand powered | Fixed former, mounted | n/a | 1.8 | about £199.96 | View offer |
 KATSU Tools KATSU 12 ton hydraulic pipe bender, 6 dies | Manual hydraulic | Hydraulic ram | 2.75 mm to 4.5 mm | 6.4 | about £119.99 | View offer | |
 DRAUXI DRAUXI manual rolling machine, TR40 | Bullet says manual. Technical table says AC | Roll. Listing also says sheet and plate rolling | n/a | 0.2 | about £345.79 | View offer |
On this page
Before you pump
Seat the die and pin the rollers before any stroke. Sealey’s PBS99 instructions make that the first mechanical check: the die sits in its place, the rollers are pinned, and only then do you bring the ram up. Lay the pipe square on the die, not perched on one edge. Put the centre of the bend over the centre of the die. A chalk line on a 1/2 inch tube stops the apex wandering as the ram rises. If the pipe is off centre, one KATSU review describes a fastener leaving the ram. That is a buyer’s report, not a procedure, and it is a reason to reset before you load the frame.
Keep fingers off the die and the rollers. A UK hire leaflet from Frank Key tells you to stay clear of the crush point, not to slide the pipe once it is under pressure, and not to bend two pipes in the same pass. Clarke and Sealey both print the release valve the same way: anticlockwise opens it, clockwise closes it. Read the plate on the machine in front of you before you copy that direction. Which former belongs on which tube is the pipe bending machine buying guide.
One bend on a manual hydraulic ram
Open the release, set the pipe, close the valve, pump gently, then open the valve to let the ram back. Clarke’s CHV12B manual is the plain version of that order, and it adds a limit people skip: do not slide a tube over the pump handle. A cheater bar overloads the linkage and the relief valve, which Sealey tells you not to alter. If the supplied handle cannot finish the bend, the die, the wall or the machine is the wrong match.
The KATSU listing states no angle, so you cannot treat a full stroke as 90 degrees. Mark the start, pump a little, and check the pipe against a set square. Release the pressure before you reposition. Store the kit upright with the ram down, as Clarke prints, so air does not enter the cylinder. None of this is a bleed sequence for a KATSU, because that sheet was not on the listing. If your own manual disagrees, follow the machine you are holding.
Oval pipe, a soft pump and sand
An oval bore after a ram bend is common on this geometry. Sealey’s manual says ovality and creasing are largely unavoidable and are not a fault of that class of bender. The former supports the inside and the ram pushes the back, so the sides flatten, especially on a short radius. That line is about the machine, not about a water fitting being workmanlike. An oval tube on a drinking-water line can still be the wrong result. If thin conduit has gone flat in a gas-pipe die, the mismatch is on the bending steel pipe page. A slower pump will not thicken the wall.
A soft pump often means air in the ram, particularly if the frame was laid on its side in a van. Clarke treats bleeding as the step only when the ram will not build pressure, and only with the hydraulic oil that manual names. Do not pour in brake fluid. Sealey forbids it. Do not invent a bleed on a machine that arrived without a sheet. Sand is optional. Sealey says a pipe packed and capped may help. It does not promise a round bore, and it is not how you bend 15 mm copper on a steel die.
When you stop
Stop if the job is gas installation pipework. Owning a ram does not make you competent to alter a boiler run or any other gas fitting. That limit is the Gas Safety (Installation and Use) Regulations 1998, and it is set out with the steel sizes on the steel-pipe page, not as a step in this sequence. Stop if the metal is cast steel. The Frank Key hire leaflet says cast steel can shatter under a ram. You do not try a small bend to see. Stop if the frame arrived twisted or if a pin, a roller or a fastener is already out of place.
Stop if an employee is using the bender without training. The Provision and Use of Work Equipment Regulations 1998 apply to work equipment, including a hired ram on a paid job. A three-roll nip is a different hazard, covered on the roll bender versus hydraulic pipe bender page. On the ram, Sealey still wants gloves against sharp steel, and still wants those hands off the die while you pump.
Follow the machine you are holding
Use the Clarke and Sealey order only as a class guide: die seated, rollers pinned, pipe centred, release closed, then a gentle pump. The KATSU ram is the top pick and the best value in this set when the printed BSP die and the 2.75 mm to 4.5 mm wall match the tube, and that is a buying fact, not a reason to ignore a missing instruction sheet. If the plate, the manual or the frame disagrees, stop. The awards rank only these three stored listings.
Common questions
Which way do I turn the release valve?
Clarke and Sealey print the same direction: anticlockwise opens the release and lets the ram retract, clockwise closes it so the pump can build pressure. Read the plate on your own cylinder before you rely on that. The KATSU listing we stored did not include an instruction sheet, so their printing is a class guide, not a substitute for the sheet in your box.
Where do I put the centre of the bend?
Put the centre of the bend on the centre of the die, with the pipe square in the groove and the rollers pinned. A chalk mark on the apex stops the tube creeping as you take the first strokes. If the pipe sits to one side, reset it with the release open. One review links an off-centre pipe to a fastener leaving the ram.
Why has the pipe gone oval?
Sealey says ovality and creasing are largely unavoidable on this type of hydraulic ram, and that this is not a fault in the bender. The sides of the tube are unsupported. A thin wall, a die that is too big, or conduit in a steel former makes it worse. A round result is not guaranteed, and an oval bore can still be unfit for a water fitting.
Should I fill the pipe with sand?
You may, as a trial, if you pack it fully and cap the ends. Sealey offers that as something that may help, not as a cure. It is not a required British method, and it is not how you bend thin-wall copper on this machine. If the wall is below the listing’s minimum, sand will not put the tube back inside the specification.
The pump feels soft. Is that air?
It may be. Clarke tells you to store the bender upright with the ram down so air stays out of the cylinder, and to bleed only when the ram will not build pressure, using the hydraulic oil the manual names. Do not use brake fluid, and do not copy a bleed from another brand onto a machine with no sheet. If pressure will not build after you have followed your own manual, stop using it.
Can I add a tube to the handle for more force?
No. Clarke’s CHV12B manual tells you not to extend the pump handle. Extra leverage loads the linkage and the relief valve, which Sealey tells you not to adjust. If the handle that came with the machine cannot finish the bend, the pipe is too heavy for the die, or the ram is not building pressure. Change the setup, or stop.
May I bend a gas pipe myself once I own the machine?
No. Gas fitting work, including installation pipework, is not a DIY bend you unlock by buying a 12 ton frame. Competence sits in the Gas Safety (Installation and Use) Regulations 1998, and the approved class for employers and the self-employed is Gas Safe registration. A householder does not alter a gas installation with a hired ram. A frame that arrives bent is a separate stop: return it under the Consumer Rights Act 2015 rather than pumping against a twist.
Related pages
Sources
Public UK sources and the amazon.co.uk listings compared on this page. Listings captured 21 October 2026. Updated 23 October 2026.
- HSE: PUWER overview (retrieved 23 October 2026)
- HSE: EIS7 three-roll bending machines (retrieved 23 October 2026)
- Supply of Machinery (Safety) Regulations 2008 (retrieved 23 October 2026)
- Yorkshire Copper technical guide (retrieved 23 October 2026)
- Lawton: how to bend plumbing copper tube (retrieved 23 October 2026)
- Palmer: BS EN 10255 carbon steel tube (retrieved 23 October 2026)
- Water Supply (Water Fittings) Regulations 1999 (retrieved 23 October 2026)
- Gas Safety (Installation and Use) Regulations 1998 (retrieved 23 October 2026)