When we took part in equipment tenders in the past, it was mostly enough to produce a good specification sheet and a quotation. Today the evaluation of a good many projects asks directly about the manufacturing process: how the welding was treated, what was tested after assembly, what is in the documentation pack, and whether this individual machine can be traced. The questions have become more specific, but the criterion behind them has not changed: whether the machine will work reliably on site.
The questions have moved from the specification sheet to the production process
The specification sheet answers what the machine can do; the manufacturing process answers whether the machine was really built to the drawings. The two can match perfectly on paper and differ a great deal on site. A simple example: if the joints in the vacuum system pipework are not properly sealed, nothing of it is visible from the outside. The consequence is that the vacuum level on site will not come up at all, and the customer's first reaction is to doubt the capability of the machine, when in fact the fault lies in the assembly operation.
The substance of such an evaluation is therefore to infer what actually happens in the workshop from the documents, when it is not possible to visit the workshop. That is also why the documentation pack and the test records have gained weight.
Welding and assembly: what the customer asks about
On welding, the customer is concerned with weld treatment, distortion control and whether there is a fixed welding procedure, because the welds on the oil tank and the pipework bear directly on pressure resistance and sealing. On assembly, the customer is concerned with whether the pipe routing is sensible, whether the seals are fitted to standard and whether space has been left for dismantling and reassembly between the components. The answers to these questions cannot be improvised; they have to be practices that are already fixed.
Whether the factory test capability can be evidenced
Customers are increasingly willing to accept one kind of answer: not only a statement that the machine is conforming, but the test records themselves. Whether the vacuum system can reach an ultimate vacuum of ≤5 Pa, whether the flow rate can reach 6000 L/h, and whether the treated oil can meet water content ≤3 ppm, gas content ≤0.01%, breakdown voltage ≥65 kV and cleanliness NAS 1638 class 5 at the same time, all of these have to be measured at the factory. Whether the measurements can be made, and whether records are kept afterwards, directly decide whether the customer accepts the specification sheet.
| Stage the customer asks about | What the question is really about | What has to be prepared |
|---|---|---|
| Sheet metal and welding | Whether the pressure-bearing and sealing parts are reliable | A fixed welding and weld treatment practice |
| Component assembly | Whether the layout is convenient for maintenance | Assembly sequence and workstation standards |
| Electrical wiring | Whether the protection functions are genuinely effective | Measured records of the phase loss and phase sequence protections and of the overpressure audible and visual alarm shutdown |
| Factory testing | Whether the specification sheet is credible | Item-by-item test records and a description of the test oil used |
| Documentation pack | Whether the customer can carry out the maintenance itself after delivery | Manual, wiring diagram, spare parts list and wear part replacement cycles |
What the documentation pack and traceability mean
A complete documentation pack is not simply a matter of putting a few booklets into the crate. Three kinds of document are actually used on site: the wiring diagram and the operating steps, the models and the replacement conditions of the wear parts, and the diagnostic route to follow when an alarm occurs. Documents that do not match the equipment are worse than no documents at all.
On a single machine, traceability is the correspondence between the nameplate, the factory number and the test records. Where a project has several machines, or where the machines arrive in batches, this correspondence determines which test data can be pulled up for a problem found on a particular machine on site.
The way the manufacturer works has to change as well
- Write the critical operations into work instructions that can be executed, instead of relying on the feel of experienced workers and on verbal agreements.
- Change the factory testing from spot checks into a record kept for every machine, with the test items corresponding one to one to the specification sheet.
- Generate the documentation pack together with the assembly, rather than writing it up at the last moment before the machine is shipped.
- Establish the link between the factory number, the test records and any change of configuration, so that a trace can be substantiated.
These changes take a share of the working hours and do change the cost structure in the quotation. From the customer's point of view, however, being able to answer follow-up questions in detail is in itself a form of credit; in this kind of tender the award depends not only on the parameters being right but also on being able to answer the questions that are put.
When the customer starts asking how the machine was built, the manufacturer's task is not to prepare better answers but to make the production process itself able to withstand the questions.