John Crane Mechanical
Seal Spare Parts Supplier
Type 1 and 2 · Type 21 · 58U and 59U · Type 109 · Type 606 and 2100
What a John Crane type number actually tells you
Sorted by John Crane's own product navigation, which groups most of its pump seals by the flexible or secondary sealing element — elastomer bellows, O-ring pusher, PTFE wedge, metal bellows — and keeps cartridge, split and slurry seals as groups of their own. That grouping is the useful thing about these numbers: it says what the flexible member is and how the drive reaches the face, and nothing about material or size.
Type 1, 1A, 1B and Type 2
The maker calls Type 1/1A a full-convolution industrial-duty elastomer bellows shaft seal with a non-clogging single-coil spring, its drive band and drive notches keeping the bellows from being overstressed; Type 1B goes higher. Type 2 is the multi-purpose non-pusher, its spring mounted outside for a working height short enough for a very short stuffing box, with what the maker calls special balancing.
Type 6, Type 21, Type 502 and Type 2100
One flexible member, four reasons to exist. Type 21 is the general-duty seal, its drive band using a dent-and-groove pattern. Type 6 is a unitised head for small-diameter pumps, its elastomer drive ring gripping the shaft without set screws or drive pins. Type 502 is unitised for confined spaces and short glands. Type 2100 is fully unitised and heavy-duty, its bellows pressure-supported so it will not crease.
Type 58U, and 57B/58B beside it
The maker describes Type 58U as a general-purpose DIN multi-spring O-ring pusher seal, unbalanced, fitting inside the DIN 24960 l1k operating length with a suitable seat. Types 57B and 58B are the balanced members. The number gives the family and the letter the balance, so a line reading only "Type 58" has dropped the field that matters most.
Type 59U, 59B and Type 109, 109B
Type 59U is the 58 with a PTFE wedge in place of the elastomer O-ring: multi-spring, unbalanced, the maker citing EN 12756, formerly DIN 24960, with ISO 3069 and API 610. Type 59B is its balanced form. Type 109 is a shaft-mounted multi-spring wedge seal with PTFE or graphite-based wedges; Type 109B is the balanced one.
Type 606, with 609 and 604
Type 606 is a rotating edge-welded metal bellows seal, its bellows in Alloy 718 or optional heat-treated AM350, with drive lugs beneath it taking rotational drive so the bellows carries less torsional stress. The maker gives it the same design as Type 609, the version without lugs; Type 604 is the stationary one. This family appears where an elastomer will not survive the medium.
The 5610 group, 4610 and the 648 series
John Crane presents 5610, 5611, 5615, 5620 and 5625 as one universal cartridge family, the digits saying whether the flexible member is an O-ring, a bellows or a metal bellows and whether the unit is single or dual. Type 4610 is a compact single cartridge whose centralising ring replaces setting clips. Types 1648, 2648 and 3648 are the API 682-qualified single and dual cartridges.
The seal in the shaft tunnel and the seal in the engine room are not the same supplier
John Crane is a name a ship can meet on two after-sales routes: the pump seals in the engine room, still made by John Crane, and the propeller-shaft business that went to Wärtsilä in 2002. Knowing which of the two the plate belongs to decides where the enquiry goes.
The lineage is on record. John Crane's own history starts in Chicago in 1917, when the Crane Packing Company was born; TI Group acquired the remaining John Crane operations in 1987, and in 2000 the company became part of Smiths Industries. Then the marine propulsion business was sold: Wärtsilä lists its 2002 acquisition of John Crane-Lips, a supplier of marine propulsion systems, and the John Crane name did not go across with it. So a propeller-shaft seal that left the works with John Crane-Lips on the paperwork is supported through Wärtsilä today, while the seal on the cooling water pump is still John Crane.
The second consequence of that sale is easy to miss: John Crane's own industry pages run through chemical, food and beverage, mining and minerals, oil and gas, pharmaceutical, polymers, power generation, pulp and paper, refrigeration compression, and wastewater and clean water. Marine survives only as a filter in its product finder. Nothing is wrong with the seals for that reason, but the catalogue is not written around a ship, so the shipboard duty has to come from the person asking. A seal the maker documents for refinery service is being asked here to sit on a sea water cooling pump, and only the buyer knows that.
What a John Crane line resolves to
Grouped as the families divide, because the repairable parts differ: what can be renewed on a wedge seal is not what can be renewed on an edge-welded bellows.
- Primary rings and mating rings, quoted as the pair the faces were lapped against
- Elastomer bellows, in the convolution form the type carries
- PTFE and graphite-based wedge rings for the 59 and 109 families
- O-rings for the pusher families, by compound rather than by size alone
- Single-coil springs, and multi-spring and S-ring sets where the family uses them
- Drive bands, drive notch collars, retainers and interlocking tang drives
- Drive lugs and edge-welded bellows units on the metal bellows types
- Complete rotating assemblies and unitised seal heads
- Cartridge assemblies with their gland plates, setting clips and centralising rings
- Gland gaskets and bolting, flush, quench, drain, buffer and barrier fittings
- Repair kits, quoted against the assembly rather than as loose items
A repair kit reference is worth more than its contents listed loose, because it fixes what the maker means to be changed together. Where the ship's stores hold the kit number from a previous overhaul, send it: it identifies the build as well as the parts. Broader consumable routing sits on marine seals, gaskets and bearings.
The fields a John Crane 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. Each of these has stopped a seal enquiry at least once.
- The letter after the number — U or B, and whether an A or T suffix follows it
- Whether the flexible member is an elastomer bellows, an O-ring, a PTFE wedge or a metal bellows
- Whether the seal arrived as a cartridge with a gland plate, or as a head and a separate seat
- Photographs of the removed seal from the face side and the drive side
- Any repair kit or assembly reference from the last overhaul
- The pump make, model, serial number and the system the pump serves
- The shaft or sleeve diameter measured at the seal, and the gland bolt pattern
- The medium in plain words, and whether it carries solids or has been heated
- Whether the seal has run dry, or the pump been started against a shut valve
- Whether a flush, quench, buffer or barrier line is piped to the gland, and from where
- Whether the machine is single-sealed or double-sealed, and which one this concerns
- On a cartridge, the full type with its suffix — John Crane sells the 5610, 5611 and 5615 families each in plain, Q and L versions, and the plain number alone does not pick one
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. For a seal built to EN 12756 dimensions, the mechanical seal size finder gives the installation length from the shaft diameter.
Single, dual, and the vocabulary that gets the right one quoted
Most of the argument on a John Crane line is not about who supplies it, but about which arrangement the buyer is describing — and the words for that are standardised and mostly unused.
John Crane sets out the API 682 arrangements in its own words. Arrangement 1 is one seal per cartridge assembly. Arrangement 2 is two seals with the space between them held below seal chamber pressure — the buffer-fluid case, and what an engineer usually means by a tandem. Arrangement 3 is two seals with an externally supplied barrier fluid held above seal chamber pressure. Those three phrases do more for an enquiry than any amount of description, because they settle what is quoted beside the seal: a reservoir, connections and gland ports a single seal does not have. Where a ship has a double seal and the request says only "mechanical seal", the arrangement is the first thing asked and usually the reason nothing was priced.
The ordering choice sits behind that. A cartridge arrives with its working height and face load fixed at the works, and the maker's case for it is installation time and simpler maintenance — on the Type 4610 a centralising ring even takes the place of setting clips. A component seal is cheaper and has to be set by whoever fits it, which on a machine nobody on board has opened is the part that goes wrong. On route: O-rings, wedges, gland gaskets and bolting are ordinary size-and-material questions and a verified alternative can be reviewed on them; faces, bellows units, cartridge assemblies and anything inside a survey scope go to an OEM-route review. Vessel Core marks the proposed route against each line.
John Crane seals — questions buyers ask
My stern tube seal says John Crane. Who supports it?
Probably not the company on the plate. Wärtsilä acquired John Crane-Lips, the propellers, shaft seals and bearings business, in 2002; the John Crane name did not transfer with it. Pump seals are still John Crane. Say which end of the ship the seal is at — that line routes the enquiry.
Is Type 58 interchangeable with Type 59?
They are close enough to be confused and not the same seal. Both are multi-spring DIN-length seals; the difference is the secondary sealing element, an elastomer O-ring on the 58 group and a PTFE wedge on the 59. The wedge is chosen where an elastomer will not survive the medium. Whichever is fitted, the letter after the number says balanced or unbalanced.
Why does saying "Type 1 bellows seal" not narrow it?
Because most of the numbers a marine buyer meets from this maker are elastomer bellows seals. Type 1, 2, 6, 21, 502 and 2100 all sit in that family on John Crane's own pages, differing in whether the unit is unitised, where the spring sits and what gland length it will go into. The number is the useful field; the word bellows is not.
Should I order a cartridge or a component seal?
On a machine that has not been opened, the cartridge: its working height is fixed at the works and nothing has to be measured on the shaft. On the Type 4610 a centralising ring replaces setting clips. A component seal is cheaper and puts the setting in the hands of whoever fits it.
The pump has a double seal. What should the request say?
The arrangement, in the API 682 terms John Crane uses. Arrangement 1 is one seal per cartridge assembly. Arrangement 2 is two seals with the space between them held below seal chamber pressure, the buffer-fluid case an engineer usually calls a tandem. Arrangement 3 is two seals with an externally supplied barrier fluid held above seal chamber pressure. Naming it settles what is quoted beside the seal: a reservoir, connections and gland ports that a single seal does not have. Say also which of the two seals the line concerns.
Which John Crane seal parts can go on an alternative route?
O-rings, wedges, gland gaskets and bolting are ordinary size-and-material questions, and a verified alternative can be reviewed on them. Faces, bellows units, cartridge assemblies and anything inside a survey scope go to an OEM-route review. Vessel Core marks the proposed route against each line.
Is Vessel Core connected to John Crane?
No, and there is no agreement of any kind. Vessel Core holds no dealership, distribution, representation or partnership agreement with John Crane, and quoting a component against one of its designations implies no approval by the maker and no claim of interchangeability. John Crane is a business of Smiths Group plc, and its own history gives 1917 in Chicago as the start and 2000 as the year it came into Smiths.
Submit your RFQ now.
Send your John Crane mechanical seal request — the Type number as marked on the seal or pump documentation, the arrangement (single or double), whether the seal is balanced, and the shaft size measured in place. The type number and the letter after it are read back to you before anything is priced, so a line written as Type 58 does not come back quoted unbalanced when the pump carries a 58B.
