P/N: A-22075/6, Rev. 1.1
Page 27 of 45
4.1.10 O-rings and Gaskets
4.1.10.1 These must be replaced at the time of the periodic valve retest and when the valve is
disassembled.
Figure 4-12 O-rings and Gasket
CAUTION: O-ring Degradation.
O-rings develop micro-cracks, can swell or shrink,
and become harder or softer with age and chemical exposure. An O-ring that fits
loosely in the cap, or can only be pushed into the O-ring retainer with difficulty, is
quite likely not the correct size. Many of Midland’s O-rings are made on special
molds to non-standard sizes and are obtainable only from Midland.
CAUTION: Defective Parts.
If any parts appear defective, it is recommended they
be replaced, or consult with Midland for recommended repair techniques when
applicable.
4.1.11 Stem Threads and Nuts
4.1.11.1 Stem threads and nuts are 7/8-9
UNJ
thread.
UNC
nuts cannot be used.
4.1.12 Special Inspection Considerations
4.1.12.1 Previous procedures may not cover all conditions encountered in the field. Therefore, it is
the responsibility of the repair agency to obtain approval from Midland for inspection,
evaluation, repair and maintenance procedures not covered herein.
4.1.12.2 Facilities performing recommended dye-penetration and magnetic-particle testing must carry
out such testing according to a qualified procedure conducted by certified trained personnel.
4.1.12.3 Evaluation of critical component metal surfaces of the valves after cleaning, inspection and
specialized testing performed by agencies other than the repair facility are the responsibility
of the repair facility
4.1.12.4 Where numerical tolerances cannot be provided, the disposition of the internal integrity and
surface quality of parts is under the jurisdiction of the repair facility and dependent on its
experience and judgment.
CAUTION
O-rings (x2)
Gasket
