Views: 0 Author: Site Editor Publish Time: 2026-10-27 Origin: Site
A 1987 process pump moved caustic on a Tuesday. By Friday the maker had been gone fourteen years, the model pulled from the catalogue, and the seal drawing with it. The shaft still turned. The box still leaked. The number on the old seal meant nothing to anyone still in business. That is the real discontinued pump problem. Not the pump. The fit.
A seal is not bought by pump name. It is bought by the space it has to fill. Shaft or sleeve diameter, stuffing box bore, the gland bolt circle, how deep the chamber sits. Those four numbers decide whether anything seals that chest, and they outlive the company that stamped the nameplate. A plant that kept the original seal drawing has the easy case. Most do not. The drawing left with the engineer who retired, or it was never filed past a part number nobody stocks.
Three routes out of it, depending on what the plant still holds.
Route | What it needs | When it works |
|---|---|---|
Match the old seal from dimensions | The worn seal measured, or the box dimensions | Drawing lost but the part exists, or one good sample survives |
Convert to a standard cartridge | Chamber dimensions only | Legacy component seal or packed box, where a single field-fit part beats a custom build |
Retrofit the stuffing box | Gland and depth reworked | Odd chamber, no off-the-shelf seal fits |
Matching from dimensions beats chasing a part number every time. A seal specialist takes the shaft size, the box bore, the bolt pattern, and builds the faces to that, no catalogue required. The old seal in hand is the best blueprint there is. Measure the spring length, the face width, the sleeve the seal rode on, send it. A built-to-spec seal comes back in weeks, where a hunt for an obsolete OEM part runs to months or ends at a dead end.
The cartridge conversion is the one most plants actually want and rarely know they have. A legacy component seal or a packed stuffing box can often take a standard cartridge sized to the chamber. The cartridge sets its own face load and axial position at the build bench, so the field crew is not shimming a spring against a feel. That removes the part of the old job that broke most often, getting the load right by hand. For an ANSI B73 pump the dimensions were standardized, which makes the cross-reference almost a lookup. For a one-off the chamber still has to be measured, but the work moves from the pump maker to the seal maker, where it belongs.
The retrofit sits at the far end. Some chambers are shaped by a defunct design nobody builds for. Reworking the gland or deepening the box opens the door to a modern cartridge, at the cost of machine time on the pump. Worth it when the alternative is a custom seal on every failure, paid for twice.
API 682 matters the moment the service is refinery or chemical. A standard cartridge built to that standard fits where a legacy arrangement does not, and it brings the flush plans and face ratings the old seal never had. A discontinued pump in hydrocarbon service does not get a pass on emission rules because its maker closed. The seal has to meet the duty, and a built-to-spec cartridge built to the standard does.
The trap is the part number. A buyer finds the old seal tag, types it into a search, finds nothing, and decides the pump is unserviceable. The number was a convenience, not the fit. The fit is the four dimensions. Another trap is the universal claim, a seal listed as fitting everything. It fits the box on paper and galls the sleeve in the field. The chamber decides, measured, not assumed.
The decision rests on one question. Does the plant hold a sample or a drawing, or only a nameplate. Sample or drawing, match it. Nameplate only, measure the chamber and convert. Either way the seal comes from a maker that builds to dimension, not a warehouse that stocked a number.
FBU builds cartridge seals to the chamber and the duty, from a sample, a drawing, or a measured box, air tested before they leave, records riding with the unit. The discontinued pump is only a problem until someone measures the space. Send the dimensions. The seal follows.
Can a mechanical seal still be sourced for a pump the maker dropped?
Yes. The seal fits the chamber, not the nameplate. Shaft or sleeve diameter, stuffing box bore, gland bolt circle, and chamber depth define the fit. A seal maker builds to those, catalogue or not.
What dimensions replace a seal on a discontinued pump?
Four numbers. Shaft or sleeve diameter, stuffing box (seal chamber) inside diameter, the gland bolt circle and bolt size, and how deep the chamber sits. With those, a specialist builds the faces without the original drawing.
Should the old seal be matched exactly or converted to a cartridge?
Match it when a sample or drawing survives, that keeps the arrangement the pump knew. Convert to a standard cartridge when only the chamber dimensions remain, the field fit gets simpler and the face load stops being a hand job.