Bedplates, frames and jigs
The things welded not for sale but for one particular machine: a pump bedplate, saddles for a vessel, a transport frame, a jig, a cover, a guard. The sizes here come off the equipment, not out of a catalogue.
How a bedplate is put together
A pump bedplate is not a stand. Whether the motor and pump shafts end up on one axis depends on it, and on that in turn depend the life of the bearings and the coupling. That is why stiffness matters more than strength here: the frame must not work under the anchors being tightened, nor under starting.
The order of work is the reverse of what feels natural. First the frame goes onto levelling nuts and is brought to level, then the anchors are tightened, and only after that is the grout poured with a non-shrink mix. Pour first and there is nothing left to set: the concrete goes off in whatever position it found.
What jobs look like
A transport frame differs from a bedplate in being sized for lifting rather than for standing: the lugs go where the slings pass through the centre of gravity, or the load twists in the air. This is the case where an extra half hour of calculation is cheaper than one bent assembly.
A welding jig is not a product but a tool. It holds the size of a whole batch and pays for itself from about ten pieces; on three parts it is cheaper to fit each one on the bench.
Machine guards
The main thing about a guard is known to every maintenance fitter: one that gets in the way will be gone within the week. So the question is not strength — all of them have enough — but how quickly the guard opens for setting up and comes back.
A door with an interlock is the only version that works without discipline: a limit switch in the control circuit stops the machine as it opens. Everything else relies on a person closing the guard themselves — and they will only close one that does not get in the way.
Bollards stand apart: they protect not the person from the machine but the machine from the forklift. Tube 108 set in concrete goes wherever traffic passes close by — and it is very nearly the most frequent item on the list.
Where to go next
Access platforms and the stairs to them are in platforms and walkways. Tanks, pipework and ventilation are in tanks and pipework. Price, lead time and fixings by substrate are in how ordering works.
Frequently asked questions
Why does a pump bedplate need grout if it sits on anchors?
Because the anchors hold it against movement and the grout against deflection. The concrete under a bedplate is never flat, and without grout the frame bears on three or four random points. At the first start it flexes, the alignment drifts and the bearings begin to run warm. Grout goes in with a non-shrink mix after the frame has been levelled.
How accurately does the bedplate have to be levelled?
The frame itself to within 0.1 mm per metre. Shaft alignment after that is done at the coupling rather than on the frame: with a dial gauge or a laser, to the pump maker's tolerance. All the frame has to do is make alignment possible and then not pull it out again.
How does a welding jig differ from an ordinary frame?
It is not a product but a tool: its job is to hold the size of a whole batch. So it has stops and clamps, and the clearances are set with an allowance for weld shrinkage. A jig pays for itself from about ten pieces; on three it is not worth building.
Is an interlock on a guard door mandatory?
Where something dangerous moves behind that door, yes. A limit switch in the control circuit stops the machine when the door opens, and that is what separates a guard from a decorative panel. A door without an interlock will be found open and propped with a spanner inside the first week.
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