Set machining allowance based on where near-surface porosity is expected and how it will be verified after machining. Use early builds/first articles with CT (or sectioning in qualification) to map the depth and frequency of near-surface indications by feature type (contours, supports, thick-to-thin transitions, thread roots). Specify enough stock to fully remove the affected zone in critical areas, then require final-surface NDE (often FPI) and any functional leak/pressure tests after final machining. Avoid a single blanket stock value if only specific features drive the risk—call out machining stock or ‘no-porosity within X of surface’ requirements by zone/feature where appropriate.

No. HIP is most reliable for closed, volumetric porosity; planar or oxide-contaminated LOF may not bond and can remain fatigue-critical. For parts where LOF is a primary risk, the acceptance plan should emphasize preventing LOF (locked parameter sets, proven process windows, powder/atmosphere controls) and verifying with an inspection method capable of finding planar defects in the critical orientation (often CT for complex geometry; UT when applicable and qualified). If LOF is detected, disposition typically requires removal by machining (if feasible), repair only if explicitly allowed and qualified, or scrap—do not rely on HIP as the sole corrective action.

Require controls that tie each delivered lot back to the exact manufacturing and inspection conditions used in qualification. For PBF: powder heat/lot IDs, reuse limits and sieving/handling records, machine ID, build ID, parameter set revision, oxygen/moisture logs (as applicable), recoater and filter maintenance events, and any in-process anomalies with disposition. For PM-HIP: powder lot, can material/lot, evacuation/outgassing records, can weld procedure control, and the HIP/heat treat cycle record tied to the part/lot. For casting: melt/heat traceability, gating/riser revision control, and any process changes affecting feeding/degassing. Contract language should require notification/approval for changes to critical items (machine, parameter set, powder source, HIP cycle, foundry process plan, NDE method/sensitivity) and should define whether requalification or additional NDE is required after a change.