design-checklist

name	design-checklist
description	Pre-design and design review checklists by component type — shaft, gear, weld, pressure vessel, structural, fatigue-critical parts. DFMEA prompts and design gate criteria.
metadata	{"priority":5,"promptSignals":{"phrases":["design checklist","design review","design check","DFMEA","design gate","review checklist"],"minScore":4}}

Design Checklist — Complete Skill

Universal Pre-Design Questions

Before any calculation:

• What are the load cases? (static, fatigue, shock, thermal, combined)
• What is the design life? (hours, cycles, years)
• What are the operating conditions? (temperature, environment, media)
• What failure modes are critical? (fracture, yielding, fatigue, wear, buckling, creep)
• What codes apply? (ASME, AISC, AWS, API, ISO)
• What is the consequence of failure? (safety, financial, production loss)
• What safety factor is required?
• Is this a new design or a modification?

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Shaft Design Checklist

• All torque and bending loads identified per operating mode
• Critical locations identified (stress concentration sites, steps, keyways, press fits)
• Kt/Kf factors applied at every stress raiser
• DE-Goodman or ASME-Elliptic diagram checked (σ'_a/Se + σ'_m/Sut ≤ 1/n)
• Static yield check at max load: n_y ≥ 1.5
• Critical speed > 1.25× operating speed (API 670: ≥ 1.25×)
• Bearing spans optimized for stiffness and alignment
• Keyway/groove Kt included in fatigue analysis
• Press fit stress added to shaft stress state
• Material selected: Sut, Sy, HB, machinability
• Heat treatment specified: through-hardened, case-hardened (depth, hardness)
• Surface finish specified: Ra [μm] at journal, at seal

Gear Design Checklist

• Module/DP chosen from preferred series (ISO 54 or AGMA standard)
• Contact ratio > 1.2 (spur), > 2.0 (helical)
• Face width: 8m ≤ F ≤ 16m (AGMA recommendation)
• AGMA bending stress ≤ S_at × Y_J (with all K factors)
• AGMA contact stress ≤ S_ac × Z_R
• Gear ratio: ≤ 7:1 (single stage) or justify above
• Interference check: N_pinion > N_min (28 for 20° full-depth)
• Backlash specified (operational + thermal)
• Lubrication method and viscosity (AGMA viscosity grade) specified
• Center distance tolerance and gear mounting specified
• Gear material: core Brinell, case depth if surface hardened

Welded Structure Checklist

• All load paths traced through weld connections
• Throat area and effective length calculated
• Fillet size ≥ minimum per AWS D1.1 Table J2-4
• Fatigue category (A-F) assigned per AISC Table A-3 or AWS
• Weld quality level specified (VT + RT/UT for critical welds)
• Preheat requirement calculated (CE formula)
• PWHT required? (t > 38mm CS per ASME, or code requirement)
• Distortion control plan (sequence, fixturing, backstep)
• Joint details conform to prequalified (AWS D1.1 Table 4.12)?
• All accessory welds (brackets, clips) checked — stress raisers on primary members

Pressure Vessel Checklist

• Design pressure = max operating × 1.1 (or per ASME UG-21)
• Design temperature confirmed (max/min)
• Shell thickness: UG-27 formula satisfied
• Head type selected and thickness calculated (UG-32)
• Nozzle reinforcement checked (UG-36 to UG-42)
• MAWP > design pressure after all calculations
• Code: ASME Sec VIII Div. 1 or Div. 2 (if >15 psig)
• Material: P-number, Group number for fabrication
• Weld joint efficiency E used correctly (UW-12 table)
• Heat treatment: PWHT required? (t > 1.5" CS per UW-40)
• Hydrostatic test: 1.3× MAWP for Div. 1
• Nameplate data fields: MAWP, MDP, MDT, inspector stamp (U stamp)
• AI (Authorized Inspector) involved from design stage?

Fatigue-Critical Design Checklist

• Fully-reversed S-N curve (R=-1) or Haigh diagram used
• Marin equation: Se = Se' × k_a × k_b × k_c × k_d × k_e × k_f
• k_a (surface finish) computed for actual Ra or machining process
• k_b (size) applied (>8mm diameter → reduction)
• Kf (notch effect) applied to σ_a; σ_m left unmodified (ductile material)
• Mean stress correction: Goodman, Gerber, or Morrow specified
• Inspection interval defined if infinite life not achieved
• Load spectrum defined (block loading → Miner's rule)
• Critical location verified by stress concentration analysis
• Residual stress considered (beneficial: compressive from shot peen, harmful: tensile from weld)

Structural Steel Checklist (AISC LRFD)

• Load combinations: 1.2D + 1.6L; 1.2D + 1.0W + 1.0L; etc.
• Section compact/non-compact/slender classification (λ vs. λ_p, λ_r)
• Lateral-torsional buckling (LTB): L_b vs. L_p, L_r
• Web shear yielding and shear buckling checked
• Deflection: L/360 live load; L/240 total (AISC Table C-L3.1)
• Connection design matches assumed end conditions (pin or fixed)
• Base plate and anchor rods designed
• Stiffeners: do webs require transverse/bearing stiffeners?
• Camber specified if needed (>25' spans typical)

Quick Reference: Target Safety Factors

Application	n_static	n_fatigue	n_buckling
Aerospace	1.25-1.5	1.5-2.0	1.5
Automotive	1.5-2.0	2.0-3.0	—
Industrial (general)	2.0-3.0	2.0-4.0	3.0
Pressure vessel	3.5 (Sut)	—	—
Building structure	1.5-2.0 (LRFD)	—	1.67-2.0
Crane/hoist	3.0-5.0	—	—

Output

Provide: checklist against each item, ✅ = passed, ⚠️ = marginal (needs attention), ❌ = failed (redesign required), list of open items requiring resolution.