Mechanical Seal Support System RFQ Checklist

A mechanical seal support system RFQ should define the seal arrangement and system function first, then the pressure hierarchy, support fluid, heat and utility envelope, instruments, alarm philosophy, connections, mounting, materials, tests, documents, and site battery limits. A piping-plan number is useful only when these project-specific details are also controlled.

Start with the function, not the equipment list

A reservoir, cooler, pump, filter, regulator, or gauge has meaning only in relation to the seal and process. State what the support system must accomplish during normal operation, startup, shutdown, standby, cleaning, and credible upset conditions.

Possible functions include:

• maintain a suitable fluid at the seal faces;
• establish a barrier or buffer pressure relationship;
• remove generated or process heat;
• flush solids or exclude contamination;
• provide quench or atmospheric-side conditioning;
• collect and monitor leakage;
• provide gas at controlled quality, pressure, and flow;
• preserve the seal during standby or cycling.

The ISO 21049:2004 online preview includes auxiliary piping, flush/cooling, quench, barrier/buffer-fluid circulation, and instrumentation within the sealing-system scope. That structure is useful even when a project is not specified to ISO 21049 or API 682: the seal and its support equipment must be reviewed as one operating system.

Define the seal arrangement and every operating state

Attach the seal data sheet, arrangement drawing, connection schedule, and selected piping plan if one exists. Identify the inboard and outboard seal, whether the support medium is a barrier or buffer, and the intended leakage direction.

Create a pressure-state table:

State	Process/seal-chamber pressure	Support-system pressure	Required relationship	Response if relationship is lost
Pre-start	Static or vented	Initial fill/pressurization	Defined before shaft rotation	Interlock, alarm, or operator check
Normal operation	Normal range and variation	Normal controlled range	Arrangement-specific	Alarm and operating response
Startup/transient	Ramp, surge, or temporary low pressure	System response during ramp	Must remain within approved sequence	State allowed duration and action
Shutdown	Pressure decay or trapped pressure	Circulation/pressure decay	Prevent reversal or loss of required function	Vent, cool, isolate, or monitor
Standby	Static, cycling, or vacuum	Retained, vented, or maintained	Protect faces and process boundary	Inspection/restart requirement
Utility failure	Process may continue or trip	Loss of cooling, gas, power, or refill	Defined safe state	Alarm, trip, backup, or controlled shutdown

Do not use discharge pressure as a substitute for verified seal-chamber pressure. If the chamber value is estimated, identify the basis and confirmation owner.

Specify the support fluid and thermal duty

For liquid systems, state the proposed fluid or required properties, compatibility with the process and seal materials, viscosity range, freeze or boiling concerns, contamination limits, refill policy, and consequence of leakage into the process or atmosphere.

For gas systems, state gas composition, dew point or cleanliness requirement where relevant, supply range, filtration, regulation, expected consumption basis, and response to low supply.

Provide the temperatures for process, chamber, support medium, cooling utility, ambient, startup, shutdown, cleaning, and upset states. When a cooler or circulation device is required, provide the calculation basis or ask the vendor to state assumptions for heat load, fouling, approach temperature, flow, and margins. Do not combine separate product maximums into a single operating point.

The official EagleBurgmann seal supply systems overview lists quench, thermosiphon, closed-loop, pressure-booster, barrier/buffer, heat-exchanger, leakage-control, external-flush, filtration, instrumentation, and gas-system families. It demonstrates the breadth of functions; it is not a substitute for selecting the correct configuration for the duty.

List every available utility at its worst usable condition

“Cooling water available” is not enough. Record supply and return pressure, minimum and maximum temperature, available flow, water quality, fouling tendency, connection size, and seasonal variation. Apply the same discipline to nitrogen, instrument air, electrical power, steam, drain, vent, flare, and support-fluid refill.

Use a utility table in the RFQ:

Utility	Normal condition	Minimum/maximum	Quality or material constraint	Site connection
Cooling water	Pressure, temperature, flow	Seasonal and upset range	Fouling, corrosion, water chemistry	Size, rating, location
Gas supply	Pressure and available flow	Low/high supply	Composition, dryness, filtration	Size, tubing standard
Electrical	Voltage, frequency, phase	Site tolerance	hazardous-area and enclosure requirement	Termination point
Instrument signal	Analog/digital/protocol	Site standard	isolation and area requirement	Junction box or loose wiring
Drain/vent	Destination and backpressure	Maximum system backpressure	closed/open handling, materials	Connection and routing owner

State whether the plant expects backup utilities, accumulators, dual filters, redundant instruments, or automatic changeover. These features should follow the process consequence and project standard, not a generic package preference.

Turn the instrument list into an operating philosophy

For each pressure, temperature, level, or flow item, define service, range, local indication, transmitter or switch, signal, alarm or trip purpose, area requirement, materials, and tag. Identify which set points are supplied by the buyer and which are proposed by the vendor for approval.

An instrument list without an operating response can create a package that measures conditions but does not tell operators what to do. Include:

• pre-start permissives or manual checks;
• low/high alarm conditions;
• trip or controlled-shutdown conditions where required;
• normal operator rounds and refill checks;
• calibration and test access;
• response to instrument failure;
• data required for commissioning and troubleshooting.

Do not state that a particular instrument count proves regulatory or API compliance. The project specification, edition, arrangement, and risk assessment govern the required monitoring.

Freeze the vendor/site battery limits

Mark the boundary on the P&ID and general arrangement. For each interface, name who designs, supplies, installs, tests, insulates, wires, flushes, commissions, and documents it.

Interface	Vendor package may include	Site scope to confirm
Seal connections	Manifold or tubing to package edge	Final tubing to gland, supports, flushing
Cooling	Cooler and package piping	Supply/return lines, treatment, isolation
Gas	Regulator/filter panel	Plant source, isolation, header capacity
Drain/vent	Package valves and connection	Safe destination, backpressure, routing
Electrical/instrument	Devices, junction box, internal wiring	Cable, control-system logic, power, grounding
Mounting	Skid, brackets, lifting points	Foundation, structure, access, weather protection
Commissioning	Package procedure and vendor checks	Plant permit, utilities, process readiness, operators

Identify tubing and fitting standards, connection rating/facing, orientation, access for maintenance, preservation for shipment, ambient/weather exposure, vibration, lifting, and transport limits.

Define materials, fabrication, tests, and documents

List wetted and non-wetted material requirements, support-fluid compatibility, external corrosion protection, tubing, fittings, valves, vessels, coolers, instruments, gaskets, and fasteners. If substitutions are allowed, require a documented proposal before manufacture.

The RFQ should state applicable design or construction standards, required edition, inspection points, pressure or leakage tests, cleanliness/flushing, calibration, functional checks, nameplate/tagging, and acceptance records. Avoid claiming that a standard reference proves the supplier is certified or that the package is compliant before the scope has been evaluated.

Request the document package needed to install and operate the system:

• approved P&ID and general arrangement;
• component and material schedule;
• seal connection schedule and flow direction;
• vessel, cooler, valve, and instrument data sheets;
• test, calibration, and inspection records as specified;
• operating, refill, commissioning, and preservation instructions;
• spare-parts list and recommended maintenance items;
• final as-built revisions.

Require a quotation basis and exception list

Ask each bidder to state the selected system concept, design conditions, heat/flow assumptions, included equipment, instruments, materials, battery limits, tests, documents, exclusions, deviations, site data required, and lead-time starting event.

Use the mechanical seal support system page to submit the commercial package and the broader mechanical seal RFQ guide to structure the seal duty itself.

The package is ready for technical comparison only when every supplier is quoting the same operating function and boundary. Final piping-plan, pressure-system, electrical, hazardous-area, and process-safety approval remains with the qualified project and plant authorities.