Roll leaks

If these ferrules fail, or if the tubesheet overheats, the ends of the tubes will pull away from the tubesheet. The result is called a roll leak. Boiler feedwater will blow out of these roll leaks. Rerolling and seal welding the ends of the tubes, while difficult, is then the only way to stop such leaks. 

These steps reduced the steam generator pressure from 170 to 150 psi and increased the pumparound gas-oil inlet pressure from 140 to 160 psi. Liz then checked the blowdown drain on the steam generator and found it to be contaminated with the greenish gas oil. This proved that the steam generator was indeed leaking. Incidentally, there were no tube leaks. The leaks were where the tubes were rolled into the tubesheet. These are called roll leaks. 

Under the conditions described in Example 3, it becomes interesting to evaluate how much product loss X can be tolerated after 2 of the 5 years of anticipated life, for example, from roll leaks or a few tube failures, before the selection of type AISI 316 stainless steel could have been justified. 

A rolling mill drive motor failed in service. Investigation revealed the motor was short circuited by water in-leakage. This forced a prolonged shutdown, as the motor could not be replaced on site. High humidity was initially assumed to be the problem. Upon close inspection of the motor air coolers, however, it was determined that water leaked from headboxes into the air plenum spaces. Severe corrosion at tube rolls was observed (Fig. 2.9). 

Inspect the tube sheet for any signs of cracking (especially around the points of tube insertion) or leaking (perhaps from tube thinning caused by excessive, repeated, or poor tube-end rolling). 

Water-in-oil emulsion hydraulic fluids are used not only in applications such as those described above, but also where leaking hydraulic fluid could contact an ignition source such as in mines, general industry, and rolling mills (Wills 1980). They are temperature sensitive and do not withstand freezing temperatures their applications, therefore, are limited to environments where freezing temperatures do not exist. 

Chief Phillip A. Napier of the GVW Fire and Rescue Department, who also runs Napier s Hardware Store in downtown Graniteville, South Carolina remembers, We received a call that the train had possibly hit a building in Graniteville. Upon our response, I told the men to report to the station, and I would try to locate the incident site and find out what was involved. And evidently, by listening to the tapes at a later date, it is evident I was already beginning to be disoriented. I couldn t see. I called for an ambulance, and I couldn t say what I wanted it for. When I pulled up to the man on the railroad track, and rolled the window down, he told me they had had a head on collision with the train, they had a chemical leak, and he couldn t breathe. Then he fell to the ground, and later died. 

Transition joints are used to join dissimilar metals where flanged, screwed, or threaded connections are not practical. They are used when fusion welding of two dissimilar metals forms interfaces that are deficient in mechanical strength and the ability to keep the system leak-tight. Transition joints consist of a bimetallic composite, a stainless steel, and a particular kind of aluminum bonded together by some proprietary process. Some of the types in use throughout the cryogenic industry are friction- or inertia-welded bond, roll-bonded joint, explosion-bonded joint, and braze-bonded joint. 

The tubes are firmly attached to the tube sheet by rolling. After a tube is pushed into the tubesheet, a tapered tool is inserted into the open end of the tube, and forcefully rotated. The tube s diameter is thus slightly expanded. While rolling is quite effective in sealing the tube inside the tubesheet, rolls have been known to leak. 

Each lot of media must pass a growth promotion test (10 to 100 CFUs per container) following the media fill run and again after the end of the incubation period. Typically incubation of media involves a period of 7 days at 30-35°C to detect bacterial growth, followed by 7 days at 20-25°C for molds. Incubation conditions must be justified based on favored growth conditions for common environmental isolates. Prior to incubation, each unit must be inspected, with any leaking or damaged units removed. Each unit also must be rolled or inverted prior to incubation for media to contact all interior surfaces of the container. 

Testing for structural integrity and testing for tiny leaks sometimes require two different approaches. Sometimes it is necessary to find leaks in systems such as a heat exchanger, which has hundreds of tubes rolled into a tube sheet. Water drips from a hydrotest may be hard to see or correct. At other times you may need to test gasketed systems that will not tolerate moisture. 

Corrosion has resulted in leak failures of many tubes and led to several shutdowns. The corrosion attack was evident in the top 100 mm where the tube was expanded (rolled) to... 

As discussed in Chapter 6, dashboards will increasingly be used to communicate process safety metrics and performance to local line management. Such dashboards may reflect current, summary, or cumulative data (such as the number of days without a leak), current conditions (such as the fill level of a tank), or the results of the most current inspection or audit. An organization s process safety metrics can evolve in a hierarchical way so that individual indicators can be rolled up from the process level to the site level and eventually even the organizational level. Dashboards can be expected to evolve similarly to report such rolled up information to upper management. 

Because these filters (Fig. 12) are made so that the leaves can be rolled from the filter quickly, they can be easily inspected for tears in the septum, leaks around the edges of the screens or around the gaskets in the manifold, improper precoating, and so forth. If the cake is blown dry in the filter before the leaves are removed from the filter shell, the cake will usually remain on the leaves so that it can be discharged either manually or by means of a vibrator. Hydraulic capacity of the leaves is usually not a problem, because their size need not be excessively large for the larger areas. 

Tubes are fastened to tubesheets by welding, mechanical rolling, or both. However, these joints are susceptible to thermal and pressure stresses and may develop leaks. In those instances where mixing of the shell and tube fluids would result in corrosive or other hazardous conditions, special designs such as double tubesheets are used, with the space between the tubesheets vented. A double tubesheet can be used only in the following rear head designs fixed tubesheets (L, M, or N) and the outside packed head (P). Bimetal tubes are used when corrosive conditions of shell and tube fluids require the use of different metals. 

Cone sleeves are made from a laminate of aluminium foil and paper. The top of the sleeve is crimped down over a cardboard disc to form a lid after product assembly is completed. Tubes are made from cardboard coated on both sides with polyethylene. The base is heat-sealed to make it leak-proof and the top is rolled to make a rim, onto which the lid is heat-sealed. Plastic tubs and containers are used for ice cream and... 

---