I'd look at the effect of the momentum of the water. If it's a gate valve, the mass of the water against the gate, (as opposed to the mass of steam) will create a lot more drag and make it hard for the valve operator to work. In that case it would stall.
I'm trying to find out why there are different allowable stresses for copper nickel piping above and below 4.5" outside diameter. Plate allowable strengths (eg B171) seem constant so I'd think that the allowable stress of the pipe, if made from plate, should be the same if a constant efficiency...
One of the things we've seen with brass components is reapplying. Brasses with higher zinc or aluminum content in particular. This is something that occurs over time and it's dependent on media through the valve. A quick example is brass with higher zinc in seawater. Zinc is anodic and goes away...
Does anyone know why the flattening test in A106 was moved to a supplementary (S3) test in the 2006a version of the spec as opposed to the previous mandatory test?
I was working on a specific problem with spiral wound gaskets years ago where the pressure was from the outside in and I don't remember the chevron direction being discussed in any of the work I went through. What seemed like an issue for my problem was that the gasket was in a joint that was...
I've seen one company advertise a line of Belleville's that were designed for pipe flanges that, when taken to flat load, would result in a specific stress in the bolt: 45 ksi or 60 ksi etc... I think it was Key Bellevilles. I thought it was a clever way of using simple tools to provide feedback...
The 12.5% tolerance is on piping wall. For the socket welds, the weak link is the throat of the fillet weld. Depending on joint and code, the size of the fillet varies. It used to be that B31.1 would stipulate grinding the toe to get less of a stress raiser. Per Appendix D you were required to...
We had problems with integrally reinforced fitting welds (MSS SP-97). We found that a lot had partial penetration. I THINK the problem was the smaller sizes but I'd have to check that. Bottom line is that there were some sizes that seemed as though they were more problematic for the welder's and...
If you look at ASME Section VIII formulas for flanges and Taylor Forge Bulletin 502, the bolt hole size isn't accounted for in flange stresses. The exception is T bolts in slotted flanges. I'm not advocating shoddy alignment/installation but what (technically) would we look at to discourage...
The Coast Guard issues licenses and administers tests for engineers. I think I'd check there as a start for requirements. I think you'll have to sail in an unlicensed capacity for some length of time first (seaman, wiper, oiler, etc..). You might also check with MEBA (Marine Engineer's Union)...
In this forum I would use the search feature and use keywords Furmanite, Trevitest, Deluca. I'd use them separately rather than together. It's come up before and some of the stuff will give you some good ideas on proceeding. We've used Furmanite and Atlantic Group although I think Deluca uses a...
If the energy of the steam (press/temp) entering the accumulator is significantly higher than the accumulator pressure (steam leaving), then you'll tend to lose water. Think of it as an energy balance. If the energy of the entering steam per pound is higher, you won't need the same mass as that...
What method are you using to check the setpoint (in shop and online)? Years ago I read about inaccuracies associated an aux lift assist device on a valve with a thermal lip disc. The disc seat was flexible and was designed to seat better at higher temps but it created inaccuracies regarding what...
Sorry I didn't mean to indicate that the intrados/extrados applied to the ASME B16.9 fittings. I think the mfgs will need to define wall based on their mfg process so that they meet the burst test requirement. I agree that Sch 40 fittings will be matched IRT service with the Sch 40 pipe (due to...
If you're looking to get some thought on minimum thickness for the elbows, you might want to look at ASME B31.1 para 102.4.5. This gives you a min for the intrados and extrados. My guess is that it's origin is rooted in the torus formulas.
I remember wedge gate valves have some unique problems. The solid wedges can get jammed in place while they're closed when the plant comes up to temp. This can be from piping flexure that causes binding on the wedge as the valve body flexes. I hadn't heard of the stem growth but it sounds like a...
We wound up with cracking problems when we mistakenly welded 4140 to carbon steel. Maybe the preheat will help but the higher carbon content in the 4140 seemed as though it was a problem
