Crosshead extension rod wipers deserve a separate line on a mud pump inspection sheet. A note saying only “seal leak” leaves maintenance planners unsure which location was observed and which assembly must be checked. This guide explains how to turn that observation into a useful service request for NOV Type P pumps.
Identify the component and its purpose
NOV booklet 25-101131, pages 5–6, describes these wipers as the barrier between the power end and piston rod chamber: they help retain gear oil and exclude water and mud. It calls for daily inspection and replacement when leakage, lip damage or wear is evident. The booklet provides separate replacement procedures for 7-P-50 through 12-P-160 and for 14-P-220. A family name therefore does not identify the correct removal procedure.
This is a planning and inspection-documentation guide, not a replacement instruction. Use the current manual applicable to the pump serial number and installed assembly. Before touching components or opening guards, authorized personnel must follow the site's shutdown, energy-isolation and pressure-release procedure. Keep guards in place for any permitted operating observation.
Locate the finding before choosing a repair
Use the equipment drawing to identify the extension rod and wiper housing. Record the chamber or rod position using the site's numbering and viewing-direction convention. A clear location makes the finding distinguishable from a liner, piston or nearby housing leak.
Do not infer the source of liquid simply because it is visible near a seal. Describe where it was first seen and whether the observation was made while isolated or from a designated safe viewing point. If the origin cannot be established safely, mark it as unresolved and request further assessment.
Inspection checklist for a work order
The following are editorial record fields, not OEM acceptance limits.
- Identify the pump by asset tag, model and serial number.
- Link the applicable drawing and manual revision.
- Name the inspected rod position and the observed location on the housing.
- Record visible leakage, lip damage or wear, or state that the area could not be inspected.
- Attach a permitted photograph or a short location sketch when it helps identify the finding.
- Record access limitations and any adjacent observations separately from a confirmed cause.
- Assign the finding to a responsible person and link the follow-up work order.
Avoid prefilled “normal” results. A covered or inaccessible lip has not been inspected just because no liquid was visible elsewhere. Conversely, an observation of liquid is not a complete diagnosis of the source or cause.
Confirm the service procedure before requesting parts
Start with the NOV 12-P-160 catalogue page or NOV 14-P-220 catalogue page, then confirm the installed assembly using equipment records. These links are navigation aids, not evidence that an individual seal kit is interchangeable.
A focused service request should identify the assembly drawing, existing component markings and the actual observation. Ask the supplier or responsible engineer to confirm the replacement identification and applicable installation instructions. Do not choose a kit by the visible outside shape alone, or copy a removal sequence from another pump model.
Keep lubrication instructions tied to the specified operation and surface. A maintenance instruction to lubricate an assembly should not be turned into permission to coat every seal surface. Resolve unclear instructions against the current manual before work starts; this article does not supply a universal lubricant or installation method.
Close the finding with a verification record
After the authorized work, record what was assessed, the component identification used, the procedure followed and the verification result. Retain any unresolved observation instead of closing the whole record with a single “repaired.” A replaced part and a verified outcome are separate entries.
Coordinate this record with the mud pump daily maintenance checklist. The work order should also identify who is authorized to decide whether the pump can return to service. This article does not establish an allowable leak rate, wear dimension or remaining life.
Source and scope
Primary reference: NOV, How to Treat Your Type P Triplex Mud Pump, 25-101131, ©2025, pages 5–6, accessed 22 September 2026. The OEM summary covers the component's barrier function, inspection triggers and the existence of different model procedures. The work-order fields and handover suggestions are original editorial guidance. Confirm serial-number applicability and any approved modifications before using a procedure.
FAQ
Are extension rod wipers the same inspection item as a piston seal?
Use the equipment drawing to distinguish them. Identify the exact assembly and location in the work order instead of using the general label “pump seal.”
Can a visible leak establish which replacement kit to order?
No. First identify the source and installed assembly, then confirm the applicable replacement documentation. The observation alone does not determine a kit number.
What if the wiper lip is not safely visible?
Record the inspection limitation and arrange assessment under an approved isolation and access procedure. Do not remove guarding or reach toward moving rods to complete the form.
Does replacing a wiper close every contamination concern?
No. Record the repair and subsequent verification separately, and refer any remaining observations to the responsible maintenance person. Do not infer a complete condition assessment from one replacement.