AESSEAL Mechanical
Seal Spare Parts Supplier
T03 · T03U · T03DU · T04 · T04 MONO · T04D · W01 · W01U · W02 · W02U
What an AESSEAL designation actually names
Sorted as they are quoted, because the letters after each figure do not all mean the same thing: on the T group they mark an execution, and the W group is a different spring geometry altogether. Reading every suffix as a size is where an AESSEAL line goes wrong first.
T03 · T03U · T03DU
The T group is AESSEAL's taper spring family, recognised by a single tapered spring that engages the rotary head and the shaft to drive the seal, and the letters after the figure are the execution rather than a size. A seal is quoted from the shaft diameter, the face and seat materials, the elastomer and the housing dimensions together, so the code alone is a starting point and not the order.
T04 · T04 MONO · T04D
T04 is an O-ring mounted taper spring seal with a pressed head, and the MONO and D forms are separate builds. State which is fitted along with the seat type, because the rotary and the stationary halves are ordered as a pair.
W01 · W01U · W02 · W02U
The W group is AESSEAL's wave spring family, recognised by a single wave or sinusoidal spring. AESSEAL lists W01U for hygienic food and beverage pumps and W02U for chemical duty, so the pump it came from matters. Requests cover the complete seal, the stationary seat and the elastomer set; a wave spring seal is not taken as a substitute for a taper spring seal until the working length, the seat and the seal chamber have been checked against the pump.
Two spring families, three designations, and a suffix that is not a dimension
The three groups quoted here split into two spring families — taper spring on T03 and T04, wave spring on W01 and W02 — and inside the taper family a suffix letter marks a different build rather than a different shaft range.
T03, T03U and T03DU sit in the taper spring family, and the letters after the figure are the execution rather than a size — a seal against this group is quoted from the shaft diameter, the face and seat materials, the elastomer and the housing dimensions together, not read off the suffix on its own. T04 carries the same logic further: it is an O-ring mounted taper spring seal with a pressed head, and the MONO and D forms are separate builds rather than options on one part, so which one is fitted has to be stated along with the seat type before the rotary and stationary halves are ordered as a pair.
W01, W01U, W02 and W02U move to a different spring geometry entirely. The wave spring family is chosen where axial space is short, and a request against it covers the complete seal, the stationary seat and the elastomer set. A W-group line is never read as a stand-in for a T-group line on the shaft measurement alone: the working length, the seat and the seal chamber are checked against the pump first.
What an AESSEAL line resolves to
Grouped as the taper spring and wave spring families divide, because a T-group line and a W-group line are not asking for parts that fit the same housing.
- Complete taper spring seals for T03, T03U and T03DU, quoted against the shaft diameter and housing dimensions
- O-ring mounted taper spring seals with a pressed head for T04, in the base, MONO and D builds
- Stationary seats matched to the rotary half already in service, ordered as a pair on any T-group or W-group line
- Complete wave spring seals for W01, W01U, W02 and W02U, chosen where axial space is short
- Elastomer sets quoted by compound and housing dimension rather than by shaft size alone
- Faces and seats in carbon, alumina ceramic, silicon carbide, tungsten carbide or stainless steel, the materials AESSEAL's own ordering codes list, matched to the part removed
- O-rings and secondary seals for both the taper spring and wave spring builds
- Repair kits, quoted against the assembly rather than as loose items
A T03, T04 or W-group line names a spring family, not a fixed size — state the execution letter, the seat type and the shaft diameter before the rest of the kit is quoted. Broader consumable routing sits on marine seals, gaskets and bearings.
The fields an AESSEAL requisition tends to be missing
Written as an audit of the lines that come back for a second question rather than as a general checklist.
- The full designation as marked, including any U, DU, MONO or D suffix
- The full AESSEAL part number, where the box label, the pump's parts list or a previous order shows it: besides the type it carries a shaft size code and letters for the rotary face, the stationary face and the elastomer
- The shaft or sleeve diameter measured at the seal, not assumed from the code
- The face and seat materials fitted, read from the removed parts where possible; carbon against silicon carbide is a different item from silicon carbide against silicon carbide under the same designation
- The elastomer compound — nitrile, EPR or Viton on AESSEAL's own lists — since it is coded into the seal part number and a different compound makes a different part
- The housing or stuffing box dimensions, for the seat and elastomer set to be matched correctly
- Photographs of the removed seal from the face side and the drive side
- Whether a stationary seat was supplied with the seal, or is being ordered separately
- The pump make, model, serial number and the system the pump serves
- Whether a taper spring or a wave spring is fitted — a single tapered coil spring, or a single wave spring — read from the removed seal or its photograph
- Whether the machine is single-sealed or double-sealed, and which one this concerns
- Vessel and IMO number, the port and the ETA
Tools for this equipment: the mechanical seal material code for the face, seat, secondary seal and spring letters, and the O-ring size finder for the secondary O-rings. Where a component seal is built to EN 12756 dimensions, the mechanical seal size finder gives its installation length from the shaft diameter.
What is fitted decides the route, not just the group it is quoted from
An AESSEAL line splits along the spring family and the execution actually fitted, and that is not always obvious from the figure alone.
Where a T04 line is quoted, the base, MONO and D forms are separate builds rather than options on one part, so a request that only names T04 has to be reopened to establish which is fitted and what seat type goes with it. Where a T03 line is quoted, the U and DU suffixes work the same way — they mark the execution, and the shaft diameter, the face and seat materials, the elastomer and the housing dimensions decide the actual part, not the suffix on its own. A W-group line is read differently again: it is never matched against a T-group part on the shaft measurement alone, and the working length, the seat and the seal chamber are checked against the pump first.
On route: O-rings, elastomer sets and other compound-specific parts are ordinary size-and-material questions, and a verified alternative can be reviewed on them. Complete seal assemblies and stationary seats matched to a rotary half already in service go to an OEM-route review where class requirements or documentation requirements apply. Vessel Core marks the proposed route against each line.
AESSEAL seals — questions buyers ask
My old seal is stamped T03U. Is that a different size from T03?
No. T03, T03U and T03DU sit in the same taper spring family, and the letters after the figure are the execution rather than a size. A seal is quoted from the shaft diameter, the face and seat materials, the elastomer and the housing dimensions together, so the code alone is a starting point and not the order.
What is the difference between T04, T04 MONO and T04D?
They are separate builds rather than options on the same part. T04 is an O-ring mounted taper spring seal with a pressed head. State which is fitted along with the seat type, because the rotary and the stationary halves are ordered as a pair.
Can a W02 seal be fitted in place of a T-group seal on the same shaft?
Not by assumption. The W group is AESSEAL's wave spring family and the T group its taper spring family, and a W02U is only considered for a T-group position once the working length, the seat and the seal chamber have been checked against the pump. Requests against the W group cover the complete seal, the stationary seat and the elastomer set.
Is a stationary seat included when a taper spring or wave spring seal is ordered?
State it either way rather than assuming it. A complete seal across the T03, T04 or W group is read as the rotary head and the matching stationary seat together, but whether the stationary is being renewed or is already in service still needs to be confirmed before the pair is quoted.
Does the AESSEAL designation tell you the face materials and the elastomer?
No. Under the same designation, carbon against silicon carbide is a different item from silicon carbide against silicon carbide, and the O-ring or diaphragm compound is ordered separately from the seal. Read the face and seat materials from the removed parts where you can, state the elastomer compound, and add the shaft diameter measured at the seal and the housing dimensions.
Is Vessel Core connected to AESSEAL?
No, and there is no agreement of any kind. Vessel Core holds no dealership, distribution, representation or partnership agreement with AESSEAL, and quoting a component against one of its designations implies no approval by the maker and no claim of interchangeability.
Submit your RFQ now.
Send the full designation as stamped on the seal or in the pump's maintenance manual, the shaft diameter, and the face and seat material if known. A photograph of the removed seal covers most of what is needed to tell the taper spring and wave spring families apart.
