Seals, couplings and bearings

Seals control leakage, couplings transmit torque between shafts, and bearings support rotating elements. These components perform different functions but must work together within the machine's alignment, loading and lubrication arrangement.

Typical applications

Pumps, compressors, turbines and industrial drives use these parts during new assembly and maintenance. Replacements usually depend on exact machine and component identification.

Types and configuration choices

Dimensions alone may not establish interchangeability. Material, speed, load, seal configuration and the manufacturer's part revision help distinguish otherwise similar components.

Define the boundary of each rotating-equipment spare

A maintenance request can use the same word for different purchasing units. A seal may mean a complete cartridge, a set of replacement faces or a repair kit. A coupling enquiry may concern a complete assembly or only its replaceable element. A bearing line may require one component or an identified set for a particular machine position. Define the unit before comparing prices. State the quantity per machine and the number of machines, and keep contingency spares separate from the parts needed for one overhaul.

Where a kit description is uncertain, request an itemized contents list against the assembly drawing. The list should show which existing parts will be retained and which parts the offer replaces. Ask whether the quotation assumes inspection of the removed assembly before the final repair scope can be established. Keep that conditional repair proposal separate from the price of a new assembly. This makes a lower quoted price understandable without assuming it includes the same materials, accessories or work.

Compare a proposed substitution at the component interfaces

Begin a substitution comparison with the approved requirement and the exact offered designation. Record each proposed difference in material, construction, dimensions, interfaces and included accessories. Bearing markings can distinguish variants within an otherwise similar range, so preserve the full identification and ask the bidder to explain its proposed replacement in application terms. Do not convert a supplier's cross-reference into an engineering approval or delete a suffix merely because it is missing from a stock description.

For couplings, request a drawing that identifies the actual supplied hubs and connecting elements against both machine interfaces. For seals, connect the offered assembly and material description to the specified duty and any support-system requirements. The responsible reviewer should be able to see whether a proposal retains the existing arrangement or needs further design work. Keep questions about equipment modification separate from the purchasing comparison, and record the documents on which any eventual acceptance is based.

Keep receiving records distinct from installation acceptance

Agree the identification and documentation required with each delivery. Depending on the purchase specification, the records may include the component reference, manufacturing or batch identification, material information, dimensional evidence and product-specific storage instructions. Request the documents that identify the supplied goods rather than relying on an unrelated brochure. If a consignment includes several nearly identical variants, ask for packaging and labels that preserve the connection between each package, order line and intended machine position.

Record any shortage, damaged packaging or inconsistent marking before the goods are allocated to the maintenance task. A receiving record can establish what arrived against the purchasing description; it does not approve an unreviewed replacement or demonstrate correct installation. Mounting, alignment, lubrication, seal setup and operating release remain governed by the approved equipment instructions and the responsible maintenance team. When specialist work is needed, define it as a separate scope with its own deliverables and acceptance responsibilities.

Machine manufacturer and model

Identify the machine tag, manufacturer, model and serial number from the equipment record. State whether the enquiry concerns a mechanical seal, coupling, bearing or a package containing several component types. A pump model alone may not identify parts fitted after a previous overhaul or modification. Include the current assembly drawing and parts-list revision where available, and distinguish confirmed records from assumptions. Ask the quotation to map every proposed component to its intended position in the machine.

Existing part number or drawing

Copy the complete component designation, including prefixes, suffixes and revision markings, rather than shortening it to the most familiar number. Provide clear photographs of legible markings alongside the approved parts list. Keep the requested reference and proposed reference in separate columns when a supplier suggests a replacement or successor. Ask for a written explanation of differences and the evidence needed for technical review. A cross-reference or matching catalogue dimensions should be treated as an identification lead until the offered configuration is checked.

Shaft dimensions

Provide the relevant approved interface drawing with units, fits and tolerances. For a coupling, identify both shaft ends and the connection or hub details required by the design. For a bearing, include the shaft and housing interfaces and its assembly position. For a seal, identify the shaft or sleeve and seal-chamber interfaces. Mark dimensions measured from removed parts as observations: wear or earlier repairs may affect them. Avoid combining measurements and drawing values without showing their source and revision.

Operating speed and temperature

State the normal and limiting operating conditions available from the equipment specification, including speed and temperature with units. Add the load or transmitted-duty information relevant to the coupling or bearing, and the fluid and pressure conditions relevant to the seal. Describe any known change from the original duty. Ask the supplier to identify the application data used in its review and the missing inputs that prevent a firm selection. A component's nominal dimensions do not establish its suitability throughout the machine's operating range.

How related requirements differ

Centrifugal pumps: Centrifugal pumps move liquid by transferring energy from a rotating impeller to the fluid. Their performance is described by a pump curve linking flow and head, with efficiency and suction requirements varying across the operating range. End-suction, between-bearings and vertical arrangements address different installations. Compare duty point, available NPSH, wetted materials, seals and driver requirements.

Positive displacement pumps: Positive displacement pumps move a defined volume of fluid through repeated mechanical cycles. Reciprocating and rotary designs are used where pressure, viscosity or controlled delivery make the pumping mechanism important to the duty. Gear, screw, plunger and progressing-cavity pumps have different operating characteristics. Selection includes flow variation, pulsation, drive speed and the system's pressure-protection arrangement.

Metering and dosing pumps: Metering pumps deliver controlled quantities of a liquid into another process stream. A dosing system combines the pump with suitable valves, controls and materials to achieve the required delivery range for a particular chemical. Diaphragm and plunger arrangements, manual adjustment and electronic control are common options. Check discharge pressure, turndown, wetted materials and dosing accuracy requirements.

Compare the complete supply scope

Separate individual components, complete assemblies and maintenance kits in the purchase schedule. Ask the offer to identify the contents of each quoted unit, including any hubs, sleeves, spacers, matched components, fasteners or accessories that apply to that particular assembly. Keep engineering assessment, machining, balancing and installation outside the goods price unless they are expressly included. Confirm the required identification records, manufacturing country, packing, delivery terms and lead-time starting point. Submit the list to Oillinko for manual supplier coordination, with unresolved substitutions recorded for technical review rather than assumed to be interchangeable.

Questions before requesting a quotation

What information should be available first? Start with the intended application and the current technical specification for seals, couplings and bearings. In this category, the initial review includes machine manufacturer and model, existing part number or drawing, shaft dimensions, operating speed and temperature. Attach the relevant drawings or scope documents and identify any information still awaiting confirmation. This makes it possible to distinguish a preliminary enquiry from a fully defined purchasing or service requirement.

Can an alternative be accepted on size or price alone? A proposed alternative needs review against the required function, materials, interfaces and documented performance. Similar dimensions or a familiar brand name do not establish compatibility. State which requirements are mandatory and where an equivalent may be considered. Availability, lead time and supporting documents are confirmed for the actual offer rather than assumed from this catalogue.