Question about vessel head diameter vs cost
Question about vessel head diameter vs cost
(OP)
Hi all,
This is a question for those of you who are fabricators. I would like to know if there are standardized head sizes that we buy from head manufacturers? i.e., are head sizes comes in increments of 3" so a standard size in a 6' range is 6'-3", 6'-6", etc?
If so, then would the cost be significantly higher if I order a vessel head of 6'-2" as opposed to 6'-3"? Or it doesn't matter at all?
The reason I'm asking is a Process Eng question how should he round the metric size of a vessel from imperial units. He worried that if he calls out 1200 mm (47" or 3'-11") then the cost will go up because it is not a "standard" vessel head size. All these years, I never paid any attention to this issue. I just design the vessel based on the process datasheet numbers and the fabricators builts it without any issues.
This is a question for those of you who are fabricators. I would like to know if there are standardized head sizes that we buy from head manufacturers? i.e., are head sizes comes in increments of 3" so a standard size in a 6' range is 6'-3", 6'-6", etc?
If so, then would the cost be significantly higher if I order a vessel head of 6'-2" as opposed to 6'-3"? Or it doesn't matter at all?
The reason I'm asking is a Process Eng question how should he round the metric size of a vessel from imperial units. He worried that if he calls out 1200 mm (47" or 3'-11") then the cost will go up because it is not a "standard" vessel head size. All these years, I never paid any attention to this issue. I just design the vessel based on the process datasheet numbers and the fabricators builts it without any issues.





RE: Question about vessel head diameter vs cost
If the heads are formed with a dish pressed in the center and the knuckle rolled seperately then making different sizes is usually not that much of a problem.
Regards,
EJL
RE: Question about vessel head diameter vs cost
RE: Question about vessel head diameter vs cost
Our supplier charges by the pound and there is no premium for oddballs.