Preliminary Requirements

Safety Requirements

WARNING

IT IS THE RESPONSIBILITY OF THE OPERATOR TO OBTAIN AND OBSERVE THE MANUFACTURER'S MATERIAL SAFETY DATA SHEETS FOR CONSUMABLE MATERIALS INFORMATION. THESE CONTAIN INFORMATION SUCH AS, HAZARDOUS INGREDIENTS, PHYSICAL/CHEMICAL CHARACTERISTICS, FIRE, EXPLOSION, REACTIVITY, HEALTH HAZARD DATA, PRECAUTIONS FOR SAFE HANDLING, USE AND CONTROL MEASURES AND ALSO TO TAKE LOCAL REGULATIONS INTO CONSIDERATION.

Procedure

1. SUBTASK 70-37-04-370-001 Heat Treatment Atmospheres for Non-Titanium Parts

   1. NOTE

      The requirements specified in Table 1 are not necessary if more than 0.060 inch (1.524 mm) of stock will be removed from all surfaces after heat treatment.

      For heat-treatment atmospheres for non-titanium parts, refer to Table 1.

      Table 1. Table 1: Heat Treatment Atmospheres for Non-Titanium Parts

      		Atmospheres		Dew Point		Purity or Composition
      A		Argon or Helium		-35 deg F (-37 deg C) maximum (Note 2)		99.99 percent minimum
      B		Hydrogen		-40 deg F (-40 deg C) maximum (Note 2)		99.94 percent minimum
      C		Argon or Helium + Hydrogen (Note 1)		-35 deg F (-37 deg C) maximum (Note 2)		(Note 3)
      D		Vacuum				20.0 microns Hg or lower
      E		Vacuum + Fast Cool (Note 8)
      F		Vacuum + Hydrogen + Argon or Helium (Notes 1, 3, and 9)		-35 deg F (-37 deg C) maximum
      G		Exothermic		+50 deg F (+10 deg C) maximum (Note 4)		(Note 6)
      H		Endothermic		+55 to +70 deg F (+13 to +21 deg C) (Notes 4 and 5)		(Note 7)
      I		Exothermic		0 deg F (-18 deg C) maximum (Note 4)		(Note 10)

      Note 1: Can be mixed in any proportion.

      Note 2: Must be given on gas being released from the furnace or retort work area.

      Note 3: Purity of each gas must be as specified in A and B, respectively.

      Note 4: Must be given at furnace or retort inlet.

      Note 5: Carbon potential determination can be made instead of dew point. Carbon potential must be 0.08 to 0.15 percent.

      Note 6: Propane-air mixture which has 5.8 to 6.5 percent carbon dioxide, 11.0 to 14.0 percent carbon monoxide; or, natural gas-air mixture which contains 4.0 to 7.0 percent carbon dioxide, 8.0 to 11.0 percent carbon monoxide, and not more than 1 gram sulfur for each 100 cubic feet.

      Note 7: Propane-air mixture or natural gas-air that contains 0.8 to 1.5 percent carbon dioxide.

      Note 8: Vacuum cycle (20.0 microns Hg or lower) must be ended by backfilling with either argon (dew point -35 deg F (-37 deg C) maximum), hydrogen (dew point -40 deg F (-40 deg C) maximum), argon/hydrogen mixture (dew point -35 deg F (-37 deg C) maximum), or helium (dew point -35 deg F (-37 deg C) maximum).

      Note 9: Vacuum level must be 20 microns Hg or lower before the atmosphere is put in.

      Note 10: Propane-air mixture or natural gas-air which contains 4.0 percent maximum carbon monoxide and 0.3 percent maximum carbon dioxide, 4.0 percent maximum hydrogen.

2. SUBTASK 70-37-04-370-002 Heat Treatment Atmospheres for Titanium Parts

   1. Argon.

      1. NOTE

         Maximum dew point must be given on gas that is released from the furnace or retort work area.

         Maximum dew point: -60 deg F (-51 deg C).

      2. Purity or Composition: 99.99 percent.

   2. Helium.

      1. NOTE

         Maximum dew point must be given on gas released that is from the furnace or retort work area.

         Maximum dew point: -60 deg F (-51 deg C).

      2. Purity or Composition: 99.99 percent.

   3. Vacuum.

      1. NOTE

         Specific temperature and heat treat time will be given in the specific repair instructions.

         NOTE

         Leak-up rate must not be more than 20 microns Hg/hour with vacuum chambers isolated from pumps.

         Purity or Composition: 0.5 microns Hg or less.