Ben A
Mechanical
- Sep 5, 2019
- 17
Hi, first post here but been reading the forums for quite a while.
I've recently taken on my first design engineer role with a firm that manufactures forged fittings, primarily to B16.9. I've been investigating our current proof burst tests (some dating back to the 1980s) and comparing to the current requirements in the 2018 edition of B16.9 and found them to be lacking based on my assumptions. I wonder if anyone more experienced could give some feedback on the following assumptions and question?
1. With the new material groups, we need PBTs for each material type - i.e. a carbon steel PBT can only qualify a carbone steel fitting, duplex for duplex etc. In other words our existing PBTs are no use for the work we do in stainless etc.
2. When looking at reducing fittings (elbows & con/eccentric reducers in particular), do both ends of the fitting need to fall into the acceptable range of the PBT? i.e. Big End must be in range of the PBT Big End, and Small End must be in range of the PBT Small End? Table 9.2.1-1 only refers to transition angle requirements for reducers, and no requirements for elbows.
3. Reducing Tees - 'Straight or Reducing tees of the same or more reduction in outlet size' - does this imply that the outlet dimensions do not have to fall in the qualification range of the PBT outlet?
4. For the size range (para 9.4.1), is the size based on the NPS actual diameter, bevel diameter, or body diameter? Some of our bodies are a LOT bigger than the NPS would suggest, for instance.
Any help gratefully received.
I've recently taken on my first design engineer role with a firm that manufactures forged fittings, primarily to B16.9. I've been investigating our current proof burst tests (some dating back to the 1980s) and comparing to the current requirements in the 2018 edition of B16.9 and found them to be lacking based on my assumptions. I wonder if anyone more experienced could give some feedback on the following assumptions and question?
1. With the new material groups, we need PBTs for each material type - i.e. a carbon steel PBT can only qualify a carbone steel fitting, duplex for duplex etc. In other words our existing PBTs are no use for the work we do in stainless etc.
2. When looking at reducing fittings (elbows & con/eccentric reducers in particular), do both ends of the fitting need to fall into the acceptable range of the PBT? i.e. Big End must be in range of the PBT Big End, and Small End must be in range of the PBT Small End? Table 9.2.1-1 only refers to transition angle requirements for reducers, and no requirements for elbows.
3. Reducing Tees - 'Straight or Reducing tees of the same or more reduction in outlet size' - does this imply that the outlet dimensions do not have to fall in the qualification range of the PBT outlet?
4. For the size range (para 9.4.1), is the size based on the NPS actual diameter, bevel diameter, or body diameter? Some of our bodies are a LOT bigger than the NPS would suggest, for instance.
Any help gratefully received.
