Mechanical Seal RFQ: A Duty Data Sheet That Suppliers Can Quote

A quotable mechanical seal RFQ defines the equipment interfaces, complete fluid description, normal and credible transient conditions, shaft data, operating cycle, support utilities, acceptance requirements, and commercial scope. Unknown values should be visible and assigned for confirmation. A filled form improves comparison, but it is still an input to application review—not a design approval.

Why do seal quotations become difficult to compare?

Two suppliers can answer the same short inquiry with different assumptions. One may quote a component seal against the old code. Another may include a cartridge, gland, sleeve, and flush connections. A third may assume clean water at normal temperature while the real duty includes solids, solvent cleaning, standby cooling, and pressure reversal.

The result is not three prices for the same scope.

The ISO 21049:2004 online preview explains that purchaser decisions and information should be shown on data sheets or stated in the enquiry or purchase order. API’s official announcement for the fourth edition of API 682 likewise assigns responsibility to the purchaser or seal vendor to ensure that the selected seal and auxiliaries suit the intended service. These references do not make every project an API service; they show why the enquiry must expose the actual duty.

Identify every value as confirmed, estimated, or open

An RFQ should communicate confidence as well as numbers. Add one of these status codes beside material inputs:

Code	Meaning	Required action
C — confirmed	Controlled drawing, current instrument data, approved specification, or verified record	Quote against the stated value and reference
E — estimated	Engineering estimate or historical operating value	State design margin or confirmation needed
M — measured	Field measurement or sample dimension	Record method, date, equipment, and uncertainty
O — open	Not yet known	Supplier lists assumption; buyer assigns confirmation before release

A blank field is not neutral. It encourages each bidder to create a different scope. If seal-chamber pressure is unknown, say so and provide suction/discharge conditions, pump curve or equipment data, and the person responsible for confirming the chamber value.

Equipment and installation data

Begin with a unique equipment identity. State the plant or project, equipment tag, pump or vessel manufacturer, model, size, serial number, arrangement, shaft orientation, and direction of rotation viewed from a named end.

For a pump seal, include:

• shaft or sleeve diameter and applicable tolerance or drawing;
• seal-chamber drawing, register, depth, bore, bolt pattern, and available space;
• stationary-seat housing and gland interface for component seals;
• sleeve, gland, bolt circle, setting length, and connection orientation for cartridges;
• existing seal manufacturer/code, construction, materials, and service history;
• shaft runout, end play, sleeve condition, and bearing concerns when replacing a failed seal;
• coupling, guard, removal, and installation access constraints.

A pump model alone may not define the installed chamber or shaft option. Attach a nameplate photograph and controlled drawing, then identify any field modification. When no drawing exists, provide a dimensioned sketch and photographs with scale and orientation.

Fluid and process data

Do not reduce the process description to “water,” “oil,” “acid,” or a trade name. The seal vendor needs enough information to screen every wetted face, secondary seal, metal, gasket, spring or bellows, and support fluid.

Record:

• chemical names, concentrations, mixture range, and water content;
• contaminants, dissolved gases, cleaners, and trace constituents that matter;
• solids content, particle character, fibers, crystals, or slurry behavior;
• density, viscosity, and vapor behavior at relevant conditions when available;
• polymerization, coking, crystallization, freezing, or deposit tendency;
• toxicity, flammability, emissions, hygiene, and contamination constraints;
• compatibility restrictions for flush, quench, buffer, or barrier fluid.

Attach the safety data sheet when useful, but do not assume it contains the process concentrations and physical behavior needed for seal selection.

Normal, startup, shutdown, and upset conditions

A single design pressure and temperature can hide the event that controls the seal. Separate the operating states.

Operating state	Pressure data	Temperature data	Other conditions to state
Normal steady operation	Suction, discharge, and seal-chamber pressure	Bulk and chamber temperature	Speed, flow, solids, available flush
Startup	Initial chamber and support-system pressures	Cold or preheated condition	Venting, priming, acceleration, dry exposure
Shutdown	Pressure decay and trapped pressure	Cool-down profile	Reverse rotation, siphon, drain-down
Standby	Static or cycling pressure	Ambient, heated, or cooled state	Shaft movement, flush availability, product setting
Cleaning or steam-out	Cleaning pressure and sequence	Cleaning maximum/minimum	Cleaning media, duration, stationary or rotating
Credible upset	Maximum differential and reverse pressure	Excursion temperature	Loss of cooling, flush, barrier pressure, or flow

Do not combine unrelated maximums into one impossible operating point. If maximum pressure occurs only at a low temperature and maximum temperature occurs at a lower pressure, show both cases.

Rotation, speed, and operating cycle

State shaft diameter, rotational speed range, direction, variable-speed operation, reversals, starts per day or batch, continuous hours, standby periods, and expected maintenance interval. For mixers and agitators, add entry orientation, radial movement, axial movement, shaft runout, bearing location, and the batch pressure/vacuum cycle.

If the seal sometimes runs with vapor at the faces, during empty-vessel cleaning, or while a pump loses prime, describe that condition rather than calling the service continuously liquid-lubricated.

Arrangement, leakage objective, and support utilities

If the arrangement is already specified, name the governing drawing or project standard. If not, state the objective and constraints instead of prescribing a plan without enough data.

Useful objectives include containment of a hazardous product, exclusion of atmosphere, prevention of product contamination, collection of normal leakage, avoidance of process dilution, or operation when the process is a poor face lubricant.

List available utilities with their normal and minimum/maximum conditions:

• clean flush or process-compatible liquid;
• cooling water supply and return;
• nitrogen, instrument air, or other gas;
• buffer or barrier fluid and refill policy;
• electrical supply and instrument signals;
• drain, vent, flare, collection, or safe disposal connection.

For a packaged system, define battery limits, connection standards, instruments, alarm philosophy, local versus remote indication, mounting, tubing material, ambient conditions, and site responsibility for final hook-up. The seal support system page provides a commercial overview of these package interfaces.

Materials, standards, and acceptance records

Separate mandatory materials from preferences and proposed alternatives. If the existing face pair or elastomer is unknown, do not invent it from color. Ask the supplier to identify the basis for the proposed material schedule and list all deviations.

State which standards and editions actually govern the project. A request to “meet API” is incomplete if the buyer has not defined applicable category, arrangement, data sheets, testing, documentation, auxiliaries, or exceptions. Conversely, do not impose a petroleum-industry standard on a general-service pump only to make the RFQ appear rigorous.

Define the required records before quotation:

• approval or outline drawing;
• material schedule and requested certificates;
• dimensional or critical-interface report;
• assembly, leakage, or pressure test and acceptance basis where applicable;
• installation, operation, and maintenance instructions;
• connection schedule, P&ID, instrument data, and general arrangement for support packages;
• marking, nameplate, preservation, storage, and packing requirements.

The Hydraulic Institute mechanical-seal guide is a useful reference for the vocabulary connecting selection, piping plans, installation, commissioning, failure observation, and troubleshooting.

Commercial fields that change the technical quote

State quantity, prototype or first-article needs, annual demand, spare strategy, destination, required date, Incoterms if already decided, packing environment, and whether partial delivery is useful. Identify whether a used sample can be disassembled or tested and who pays for return shipping.

Require every offer to list:

Quotation field	Required supplier response
Technical basis	Documents, duty values, and assumptions used
Included scope	Seal, gland, sleeve, adapters, gaskets, instruments, spares, documents
Exclusions	Site work, piping, commissioning, tests, or documents not included
Deviations	Difference from drawing, material, standard, inspection, or delivery request
Open points	Information required before order or production release
Validity and lead time	Starting event, approval dependency, and delivery basis

Release a common scope before comparing price

Use the RFQ response to close technical queries, not just collect totals. Normalize arrangement, interfaces, materials, support-system boundary, documentation, testing, spares, and delivery before ranking suppliers.

For a chemical duty, the mechanical seal selection guide explains the separate arrangement and material decisions. For an unknown legacy part, first complete the identification workflow.

The RFQ is ready for order only when critical unknowns have an owner and deadline, vendor exceptions are explicit, and the approved technical scope can be carried into the purchase order without losing its revision or assumptions.