0 votes
122 views

2 Answers

0 votes
answered Mar 4, 2016 by TPham (5,010 points)

End Connections

  • Threaded and socket welding end connections should be limited to NPS 2 and smaller.
  • Valves larger than NPS 2 should be flanged except: 
    • Steam services requiring Class 600 and above may have buttweld ends.
    • Use of buttweld ends for services other than steam for Class 600 and above should require review and approval.
  • Surface finish on raised face flanges should be 125 to 250 micro inches Ra.

Threaded Openings and Plugs

  • Threads should be per ASME B1.20.1.
  • All threaded openings should be plugged with solid, round or square head plugs of wrought material having the same nominal composition as the body or a comparable material.  Plugs should not be made from cast material.
0 votes
answered Mar 5, 2016 by TPham (5,010 points)

Nodular Iron, Cast Iron, Aluminum, and Copper Based Alloy Valves

  1. Nodular (ductile) iron valves, either austenitic or ferritic, should only be used within the limits of ASME B31.3 provided the installation is approved.  Usage in hydrocarbon or dangerous material services requires review and approval. Restrictions on the use of ductile iron, cast iron and low melting point material valves are necessary to prevent their failure in the event of a fire.  Such a failure would either feed the fire or interrupt flow of a required utility, unnecessarily increasing the hazardous condition.
  2. Cast iron valves may only be used in water service not subject to freezing. Restrictions on the use of ductile iron, cast iron and low melting point material valves are necessary to prevent their failure in the event of a fire.  Such a failure would either feed the fire or interrupt flow of a required utility, unnecessarily increasing the hazardous condition.
  3. Aluminum and copper based alloy valves (e.g., brass or bronze) which experience significant loss of mechanical properties at elevated temperatures should not be used in the following services:
  • Services in which failure of the valve in a fire would increase the hazardous condition (Examples: Prevent steam flow to any process pump, steam header, or emergency steam line.)
  • In hydrocarbon service

Related questions

1 answer
3 answers
asked Jun 4, 2015 in Engineering by TPham (5,010 points)
1 answer
...