Pre-Weld Calibration Protocol

Territory-grade tolerances for structural steel. No shortcuts.

WARNING: Rush the pre-heat, crack the frame. Rush the cool, shatter the joint. This protocol is non-negotiable.

Detailed view of torch welding metal surface, featuring blue flame. — Fig 1.1 — Torch geometry and electrode alignment. Note the 75-degree angle.

I. Pre-Heating (0–15 min)

The base metal must reach 300°F (149°C) before the first arc strike. Below this threshold, thermal shock fractures the grain.

Material	Min Temp	Hold Time	Sensor Placement
A36 Steel	300°F / 149°C	10 min	2" from joint
1018 Alloy	350°F / 177°C	12 min	3" from joint
Stainless 304	400°F / 204°C	15 min	Direct contact

Source: AWS D1.1 Structural Welding Code §5.2 (Wikidata Q28304891)

II. Arc Geometry (15–30 min)

Maintain 75° torch angle. Feed rate fixed at 6 inches per minute. The puddle breathes—it does not boil.

TORCH_ANGLE = 75 deg ± 2
FEED_RATE = 6.0 in/min ± 0.1
POOL_TEMP = 4200°F ± 50
VOLTS = 22.0 ± 0.5
AMPS = 145 ± 3
  

III. Controlled Cooling (30–45 min)

Cover the bead with dry silica sand immediately upon extinguishing the arc. Allow 45 minutes of passive cooling. Forced cooling voids the warranty of the joint.

Step	Action	Tolerance	Failure Mode
0s	Extinguish arc	N/A	Thermal shock
+5s	Apply sand blanket	±2mm thickness	Crack propagation
+2700s	Remove cover	<100°F ambient	Brittle fracture

IV. Verification

Every joint undergoes magnetic particle inspection before load testing. Any indication of discontinuity exceeds 0.5mm requires re-weld.

IF defect_width > 0.5mm THEN REJECT
ELSE IF tensile_strength < 70ksi THEN REJECT
ELSE PASS
  