Odd size fitting

[kennyd]

It looks like a 1/2" BSPP (British Standard Pipe Parallel) to me.

According to my charts, that will be a 13/16-14 thread.

The only thing that looks odd in your picture is the O-Ring. Usually, BSPP fittings have either a bonded seal (metal washer with rubber seal) or a captive O-Ring held in place with a metal washer.

Could be the captive washer is gone from your fitting, but otherwise, going from the dimensions and photo you supplied this looks exactly like 1/2" BSPP.

I did not pick BSPP because the major diameter he stated was .811", and a 1/2" BSPP should be .8250", and 13/16" is .8125 in decimal.

 

[Discount Hydraulic Hose]

I did not pick BSPP because the major diameter he stated was .811", and a 1/2" BSPP should be .8250", and 13/16" is .8125 in decimal.

I have the "what size is your thread?" conversation almost daily with customers who are having trouble identifying their fittings. In my experience, a variation of 10 or 15 thousandths of an inch is completely negligible and even to be expected. Depending on the precision of the measuring method (or the individual taking the measurements), even larger discrepancies are not uncommon.

 

[Discount Hydraulic Hose]

I have the "what size is your thread?" conversation almost daily with customers who are having trouble identifying their fittings. In my experience, a variation of 10 or 15 thousandths of an inch is completely negligible and even to be expected. Depending on the precision of the measuring method (or the individual taking the measurements), even larger discrepancies are not uncommon.

I should add, the thread size reference I have here in the office doesn't even show thousandths. Dimensions are only given to two decimal points. A measurement of .81 instead of .82 wouldn't give me any hesitation at all. I would consider that a direct hit, especially if the threads may have been worn from use.

 

[kennyd]

I have the "what size is your thread?" conversation almost daily with customers who are having trouble identifying their fittings. In my experience, a variation of 10 or 15 thousandths of an inch is completely negligible and even to be expected. Depending on the precision of the measuring method (or the individual taking the measurements), even larger discrepancies are not uncommon.

I should add, the thread size reference I have here in the office doesn't even show thousandths. Dimensions are only given to two decimal points. A measurement of .81 instead of .82 wouldn't give me any hesitation at all. I would consider that a direct hit, especially if the threads may have been worn from use.

Roger that HHG, You certainly have more experience than me:thumbsup: I was just saying why I did not pick the BSPP, not questioning your doing so For Tony's sake, I sure hope you are correct so he can finish his project.

 

[TonyF]

Roger that HHG, You certainly have more experience than me:thumbsup: I was just saying why I did not pick the BSPP, not questioning your doing so For Tony's sake, I sure hope you are correct so he can finish his project.

No worries, I doubled checked everything. Once I knew where to look that is. Thanks.

On your discussion of sizes and measurements, one factor which comes into play is that there is a fit tolerance on all threads. I have no idea what it is on BSPP fittings or any other fitting for that matter. But on commercial nuts and bolts its usually 2a or b. If the major diameters of both male and female threads are exactly the same, it will never thread properly, likely not even start. So any thread diameter measured with a caliper or mic is not likely to be exactly on its spec'd size.

Anyway, a solution arrived today from McMaster, 13/16 -14 (1/2) BSSP as thought and JIC 8, 3/4-16 on the other. I already had the 8 to 6 JIC adapter. I also noticed that a recess is machined into the pipe on the excavator, hence no washer.

I ordered some adapters from Dis Hyd Hose to go directly from the 1/2 BSPP to JIC 6 - they should be here tomorrow. I'd rather use those as there is one less connection point.

Thanks for the help everyone. Hopefully, I can put the machine to good use over the weekend.

Tony

 

[TonyF]

To bring closure, everything fit.

 

[Discount Hydraulic Hose]

Roger that HHG, You certainly have more experience than me:thumbsup: I was just saying why I did not pick the BSPP, not questioning your doing so

No problems, Kenny. I didn't take it as a challenge. I just thought it would be useful to share the info.

With all of the different thread standards floating around (NPT, JIC, BSP, and so on), measuring thread ODs is often the best way to identify a fitting. Because of that, I've noticed that most of the standards are substantially different enough from one another (usually 1/16" or more). A measurement that's off by one or two hundredths shouldn't lead you to the wrong fitting.

 

[Discount Hydraulic Hose]

On your discussion of sizes and measurements, one factor which comes into play is that there is a fit tolerance on all threads. I have no idea what it is on BSPP fittings or any other fitting for that matter. But on commercial nuts and bolts its usually 2a or b. If the major diameters of both male and female threads are exactly the same, it will never thread properly, likely not even start. So any thread diameter measured with a caliper or mic is not likely to be exactly on its spec'd size.

If you're dealing with a fitting that's already been in use, thread wear can come into play as well.

For our purpose, the references we use always specify the "peaks" of the threads (OD on the male threads, and ID on the female threads). Because of the interlocking nature, the female thread ID is actually SMALLER than the male thread OD. Both dimensions are shown on our size charts, so you can measure a female fitting just as easily as a male one.