TL;DR
Identify whether the installed NOV Type P piston-liner cooling circuit is single-pass or recirculating before preparing its maintenance record.
- NOV describes single-pass cooling with cool, clean fresh water; its recirculating alternative requires particular attention to coolant cleanliness and temperature.
- For a recirculating circuit, record reservoir service and the associated coolant header separately. NOV identifies piston failure as a general prompt to change coolant and clean the reservoir.
- A visible spray does not confirm acceptable coolant condition. Use the current equipment-specific instructions for coolant selection and acceptance limits.
These points summarize NOV booklet 25-101131, pages 14–15. The worksheet below is our editorial recommendation, not an OEM acceptance form.
Scope: confirm the installed circuit
Use the pump nameplate, serial number and applicable system drawing to establish the actual circuit. This guide concerns coolant management; it provides no mixture recipe, retrofit approval or return-to-service authorization. Modified equipment requires its own approved documentation.
For catalogue navigation, see NOV 12-P-160 and NOV 14-P-220. A catalogue entry does not prove the installed coolant configuration. Any intrusive inspection or servicing requires authorized personnel, shutdown, energy isolation and verified pressure release under the site's approved procedure. Operating observations must use approved viewing points with guards in place.
What differs between single-pass and recirculating cooling?
The distinction is whether coolant is used once or returned through the circuit. On page 14, NOV describes fresh-water single-pass cooling as avoiding reheating and reuse of coolant contaminated by drilling mud or debris. Page 15 discusses recirculating cooling when single-pass fresh-water use is impractical and emphasizes keeping the coolant clean and cool. Primary reference, pages 14–15.
Record the circuit identified by the applicable drawing, including unresolved differences found on the equipment. Do not infer coolant suitability from colour, a component label or a pump family name. Coolant selection, handling and disposal remain governed by the applicable instructions and site requirements; this article does not prescribe a formulation.
What should the reservoir service record cover?
Record the reservoir and coolant header as separate items. NOV page 15 discusses removing accumulated mud, sand and debris from the reservoir as often as necessary to maintain acceptable coolant condition. It also identifies coolant renewal and reservoir cleaning after piston failure as a general rule of thumb, and includes cleaning the associated header. Primary reference, page 15.
Capture the work-order reference, the applicable procedure and the evidence of completed work. A piston-failure event is a follow-up trigger, not a diagnosis that coolant caused the failure. Do not turn the booklet's general guidance into a universal fixed service interval, temperature limit or fluid-change approval.
Handover checklist
The following are recommended documentation fields, not additional OEM specifications:
- Identity: asset tag, nameplate model, serial number and applicable drawing/revision.
- Circuit: single-pass, recirculating or unresolved; cite the evidence used.
- Coolant: approved specification reference and available condition observations; mark missing measurements as unknown.
- Service: last reservoir service and header service, each with its work-order reference.
- Event: piston failure or contamination finding requiring follow-up; keep findings separate from unconfirmed causes.
- Closure: responsible person, verification evidence and any open action.
If a location cannot be checked safely, record the limitation and arrange authorized follow-up rather than removing a guard to complete the record.
FAQ
Does visible spray establish acceptable coolant condition?
No. Spray visibility does not establish temperature, cleanliness or coolant suitability. Record those separately using the applicable instructions.
Is there a universal reservoir cleaning interval?
This guide provides none. NOV page 15 links reservoir service frequency to maintaining acceptable coolant condition and gives piston failure as a general coolant-change and cleaning prompt.
Does coolant contamination prove the cause of piston failure?
No. Record contamination as a finding. A causal conclusion requires a separate authorized investigation and supporting evidence.
Can this worksheet authorize a coolant substitution?
No. Obtain the applicable approved coolant specification and system instructions before considering a change.
Sources and related reading
Primary source: NOV — How to Treat Your Type P Triplex Mud Pump, 25-101131, pages 14–15. Source checked on 8 October 2026, Los Angeles time. The circuit descriptions and service prompts above are paraphrases; record fields and handover recommendations are editorial additions.
See the separate liner spray inspection guide for spray arrangement and viewing-location records, and rod chamber cleanliness record for chamber observations. Neither replaces equipment-specific coolant instructions.
Next step
Prepare the nameplate model, serial number, coolant-system drawing reference and the item or documentation you need. Include unresolved facts in your parts enquiry so the installed assembly and required specification can be checked before a selection is accepted.