Tag: Piping Plan 11: Operating Checks

Use this Piping Plan 11 field checklist to record operating conditions, review flush restrictions and prepare useful evidence before changing a seal or orifice.
Plan 11 takes process liquid from the pump discharge through a restriction orifice to the seal chamber. This page focuses on the information needed for an application review. For the circuit explanation, read our Plan 11 function and piping guide.
Build one operating record, not a collection of isolated readings
Record the pump tag, liquid composition, operating temperature, pump speed and operating point. Add discharge pressure and seal chamber pressure where suitable measurement points exist. Identify each measurement location and unit, and take related readings under the same stable operating condition. Mark unavailable measurements as unknown; discharge pressure alone does not establish the pressure difference available to the flush circuit.
Compare three moments in the pump’s operating cycle
Before start: Confirm that the installed piping route, gland connection and documented orifice match the approved drawing. Check the site’s filling and venting procedure. Record any recent seal, piping or process changes.
During stable operation: Log available pressure, temperature and flow readings alongside leakage observations. Compare them with the approved operating limits and a known satisfactory baseline. A warm flush pipe does not by itself prove that sufficient liquid is circulating.
After a duty change: Repeat the record when speed, product, temperature or pump loading changes. Note whether the symptom begins immediately or develops over time. This makes a review more useful than reporting only that the replacement seal failed.
Use the symptom to choose the next question
A problem appears after maintenance: Was the correct orifice reinstalled, was the line cleared of debris, and does the connection match the drawing? Check the maintenance record before assuming that a different seal material is needed.
A problem occurs only at a different operating point: How did the available pressure difference and liquid conditions change? Ask the pump and seal suppliers to review that duty as well as the rated condition.
Deposits recur in the flush circuit: What are the deposits, and when do they form? Include process changes and shutdown conditions in the review. Repeated cleaning does not establish that the same flush arrangement remains suitable.
These questions organize an investigation; they do not identify a failure cause on their own. Inspect or remove components only after the equipment has been isolated, depressurized and made safe under the site’s procedure.
What to send for an orifice or seal review
Provide the pump and seal models, an annotated piping drawing, existing orifice diameter, line dimensions, liquid properties, operating range and the dated observations above. Include photographs of removed deposits or damaged parts if available. There is no single orifice size or flush rate that this tag page can specify for every installation. A proposed change needs confirmation against the pump, seal and process requirements.
For a broader review, use our mechanical seal system checks and application review checklist, or send your operating information for discussion. Related Plan 11 reading is listed below.