Process reviews where every
safety case is traceable.
Owner’s-engineer AI reviews for oil & gas deliverables — traceable findings, comment registers and human-supervised escalation in hours. Process discipline is where relief sizing errors, HAZOP gaps, and SIL miscalculations live. We find them before the client does.
The gap that gets past HAZOP review.
Relief valve sizing cases that are not annotated against their governing scenario are the most common major finding in process reviews. The sizing calculation exists — it just is not tied back to the HAZOP action that demanded it.
Relief valve sizing case not annotated against blocked-outlet scenario
What runs, in what order.
The check sequence is discipline-specific. Process checks run across relief sizing calculations, HAZOP registers, cause-and-effect matrices, and SIL assignment worksheets — in that order.
Relief device inventory vs. P&ID
API 520 Part I §2Confirm every PSV and PRV shown on P&IDs appears in the relief device register with a sizing calculation reference. Flag orphaned devices and uncalculated entries.
Governing relief case identification
API 520 Part I §4.2For each relief device, confirm all applicable scenarios have been evaluated: fire case, blocked outlet, thermal expansion, control valve failure, utility failure, reflux failure. Check that the governing case is explicitly stated.
Relief flow rate calculation
API 520 Part I §5Verify that relief flow rate is derived from the governing scenario using correct thermodynamic assumptions (latent heat, vapour fraction, molecular weight). Flag where only fire-case sizing is presented.
Orifice size and set pressure
API 526 Table 1Cross-check the selected orifice designation against the calculated required relieving area. Confirm set pressure ≤ MAWP and accumulation within 110% per API 520.
Back pressure correction
API 520 Part I §6For conventional and balanced-bellows PSVs, check whether back pressure correction factor Kb has been applied where back pressure exceeds 10% of set pressure.
HAZOP action closeout status
IEC 61882 §7For every open HAZOP action, confirm an assigned owner, due date, and current status are in the register. Flag actions with no status update older than 90 days from IFR.
Cause-and-effect matrix completeness
IEC 61511-1 §9.3Cross-check C&E matrix initiating causes against HAZOP register deviations. Flag causes present in HAZOP with no C&E entry, and C&E entries with no HAZOP backing.
SIL target vs. calculation presence
IEC 61511-1 §11.9Identify SIL-rated functions in the SIL assignment register. For each, confirm a SIL verification calculation (LOPA or fault tree) is in the document register and references the correct PFD target.
What SpecSense flags in process reviews.
Blocked-outlet relief case not evaluated — PSV-2401 potentially undersized
HAZOP Action #112 requires blocked-outlet case for PSV-2401. Only fire case is calculated in CV-RV-2401. Pump run-out rate at shut-off head not compared to PSV orifice capacity.
SIL 2 function — no LOPA or fault tree in IFR document register
SIL assignment record SIL-003 lists High-Integrity Pressure Protection (HIPP) on V-1101 as SIL 2. No LOPA worksheet or fault tree present in IFR package. PFD target unverified.
Back pressure correction — Kb not applied on conventional PSV with 18% superimposed back pressure
PSV-3201: conventional spring-loaded valve, superimposed back pressure 4.8 bar, set pressure 26 bar = 18.5%. Kb should be applied at this ratio; calculation uses Kb = 1.0.
21 HAZOP actions with no assigned owner — FEED-to-FEED+ transition
HAZOP register PROJ-HAZ-002 Rev 4: 21 actions show status “Open” with no assigned owner and no due date. Register was issued 6 months ago with no status sweep since.
C&E matrix missing 4 initiating causes present in HAZOP register
Comparing HAZOP register PROJ-HAZ-002 to C&E matrix PROJ-CAE-001: deviations 7C, 12A, 19B, 23D present in HAZOP with safety-critical consequences have no corresponding C&E row.
Flare header pressure drop not confirmed against worst-case simultaneous relief
Flare network hydraulic calculation FLR-CALC-001 considers normal operations. Worst-case simultaneous relief scenario (fire case + utility failure) not evaluated. May not govern but should be confirmed.
What we check against.
API 520 Part I
Sizing, selection, and installation of PSVs — sizing
API 520 Part II
Installation requirements for pressure-relieving systems
API 521
Pressure-relieving and depressuring systems
API 526
Flanged steel pressure-relief valves — standard orifices
IEC 61511-1
Functional safety — SIS for process sector
IEC 61882
HAZOP studies — application guide
IEC 61508
Functional safety of E/E/PE systems — basis of IEC 61511
API 14C
Analysis, design, installation of basic surface safety systems
ISA S84 / IEC 61511
Safety Instrumented Systems in the US process industry
ASME PTC 25
Pressure relief devices — performance test codes
What we do not replace.
SpecSense checks relief sizing inputs against code requirements, HAZOP actions against register completeness, and SIL targets against calculation presence. It does not run dynamic simulation (HYSYS/UNISIM), it does not perform independent SIL verification per IEC 61508, and it does not replace the HAZOP team. It gives the OE a traceable audit of whether the documentation reflects the safety engineering — before you submit it.
Ready to run process through SpecSense?
Drop a HAZOP register, relief sizing calc, or cause-and-effect matrix. 48-hour supervised pilot. Chartered-engineer sign-off.