The water hammer this is causing in the field is allarming for a 1.5" line. This in itself would be ok if we'd reallised it at the time, but it went through the net, so that blast type traps were installed into the condensate system. From a stress point of view this works wonderfully, however, the raised loop in the condensate line (from the traps on the main steam line) meant the condensate header is constantly flooded. Now i'm no expert but i try to examine how the designers run these lines and correct any mistakes.īecause this line ran some 550m outside, the philosophy was to have the condensate expansion loops at every other steam expansion loop. Ive learnt the hard way about condensate slugging and water hammer.Ī while back i did an analysis on a steam line (the one mentioned above) and its condensate line. Avoid putting anchors at the end of a run. I either do a hand calc or fudge the friction factor (-25%) on one side of the anchor. A general rule to remember is that if you anchors are centered between loops, to add a 25% out of balance factor to the friction forces. Try also to place the lines nearest the edge of the rack so the supports can be braced more effectively at the anchors. In plants I try to keep the loops spaced to limit the growth to 6in/150mm but with longer shoes and clash checks you can go longer. If you are looking at plant piping most of that is irrelevant to your case. The forces are HUGE so do everything you can to prevent this phenomenon. Consider beefed up guides and anchors with fabreeka pads to lower dynamic load factor. Waterhammer - for some reason during start-up many operators find a way to induce waterhammer (steam bubble trapped in sub-cooled condensate collapses).
#STEAM ANCHORS AND GUIDES INSTALL#
Sometimes we center them to make sure construction can't install the offset on the wrong side. Often we also have shoes of varying length ie., 300mm, 600mm, 900mm, 1200mm, and 1500mm, and the also offset them in opposit direction of growth. The anchor-anchor spacings can be 400m+ and the loops can be 12m x 9m + depending on NPS etc. I've had shoes as long as 1.5m to handle the growth. Make sure the guides are close enough to control the movement of the pipe in a predictable way. The distance to the next guide should be far enough to prevent the prying or binding effect that occurs if they are too close. Assuming you're using "z-loops", where the lateral offsets section of the loop is at 45°, make sure the distance to the first guide on either side is far enough away to allow the loop to pull the pipe in the direction of the loop. Usually they are made with high tensile pipe (Q&T with yield of 448MPa/65ksi or 550MPa/80kis) I've designed many above ground high pressure steam pipelines (600, 900, and 1500 class, up to 24 NPS).