Hi,
Most of the references are from the earlier thread
Materials for Oxygen gas duty
thread404-77772
Note the newer NASA reference below.
israelkk, you should be aware that
MIL-DTL-2/41 is only an additional requirement to the many general valve requirements of
MIL-DTL-2F. I give a few samples of these requirements below, with relevant highlighted (bold). Especially note: You must use a forged brass body; Forging brass shall conform to
ASTM B 124/B 124M, CDA Alloy Number C37700.
btrueblood, chromium plating is required per
MIL-DTL-2/41. I'm sure it would risk CTE problems in LOX service, but for present situation, only needs testing from -60 to +160
oF (see below). I agree that Monel is superior to brass & steel in many respects, so probably wouldn't need the chromium plating, but the government standardized on a set of less expensive alloys.
MIL-DTL-2/41 - VALVE, CYLINDER, GAS: OXYGEN, OUTLET 540, MEDICAL
(PRESSURES THROUGH 3000 psig (20680 kPa) AT 120 ºF (48.9 ºC)).
“REQUIREMENTS:
TYPE DESIGNATION: V41-540-2
TABLE I. Valve requirements. [I omitted everything except composition]
Composition: A”
“SPECIAL REQUIREMENTS:
1. The valve shall be chromium plated.
2. Mark the valve body: OXYGEN MED.
3. A valve outlet cap shall be supplied.”
MIL-DTL-2F VALVES, CYLINDER, GAS (FOR COMPRESSED OR LIQUEFIED GASES), GENERAL SPECIFICATION FOR
“1.2
Classification. The valves are of the following styles, classes, compositions, inlet sizes, and pressure relief device (PRD) types.” [note: I am only listing composition as example]
“
Composition A - Forged brass body. [specified in
MIL-DTL-2/41D]
Composition B - Forged steel body.
Composition C - Forged bronze.
Composition D - Machined brass (medical post).”
MIL-DTL-2F lists a large number of 'APPLICABLE DOCUMENTS' with which you must comply:
“2.2.1 Specifications, standards, and handbook. The following specifications, standards, and handbook form a part of this document to the extent specified herein.”
I will give one since its requirement appears in Paragraph 3.4.11.8:
“NATIONAL AERONAUTICS AND SPACE ADMINISTRATION (NASA)
NASA-STD-6001 - Flammability, Odor, Offgassing, and Compatibility Requirements and Test Procedures for Materials in Environments that Support Combustion.
(Application for copies should be addressed to NASA Technical Standards, EL01 MSFC,
AL 35801 (Phone: 205-544-2448). Electronic copies of NASA publications may be obtained
from
“3.4.4
Brass.
3.4.4.1 Castings. Brass castings shall conform to ASTM B 763, CDA Alloy Numbers C83800, C84200, or C84400.
3.4.4.2 Forging. Forging brass shall conform to ASTM B 124/B 124M, CDA Alloy Number C37700.
3.4.4.3 Free-cutting. Free-cutting brass shall conform to ASTM B 16/B 16M, CDA Alloy Number C36000.
3.4.4.4 Naval. Naval brass shall conform to ASTM B 21/B 21M, CDA Alloy Number 48500.
3.4.4.5 Strainer wire. Brass strainer wire shall conform to ASTM B 134/B 134M, CDA Alloy Number 27400.”
Note: Specifications for bronze, steel and other materials are also given.
“3.4.11.8
Medical valves. The material used in all medical valves shall be in accordance with the latest revision of NASA-STD-6001 (see 6.2).”
Construction details and other requirements are given. For example,
“3.7.6
Combustibility. When intended for use with oxygen or oxidative gases, organic components of the valve, such as packing, seals, and lubricants, shall be stable when exposed to oxygen. The material shall not react, discolor, or show any evidence of change in appearance under the following conditions:
a. Exposure for 1 hour to oxygen at a pressure of 2000 psig (13790 kPa) and a temperature of 302 °F (150 °C) ±2 °F (1.11 °C).
b. Instantaneous exposure to oxygen at a pressure of 2000 psig (13790 kPa) while heated to a temperature of 160 °F (71 °C) ±2 °F (1.11 °C).”
“3.8.1.2
Storage. The valve shall withstand storage at the maximum service pressure specified herein, for 8 hours at a temperature of -60 °F (-51 °C) ±2 °F (1.11 °C) without leaking, when closed at a closing torque not greater than that specified in table III and without damage or permanent deformation of any components.”
I hope this clarifies things. Get all relevant specs. The government has already decided what alloy to use, etc.
Ken