Joint screwed

Ak ammonia piping should be standard (Schedule 40) or extra heavy (Schedule 80) steel having welded or screwed joints, respectively. Galvanized piping or brazed joints should never be used. Ammonia accepted for pipeline transportation must meet the fokowing specifications NH, 99.5 vol % min dissolved inerts, 0.16% max, ok, 5 ppm max and water, in the form of steam condensate, 0.2% min, or distiked water, 0.5% max. 

Valve bodies are also standardized to mate with common piping connections flanged, butt-weld end, socket-weld end, and screwed end. Dimensional information for some of these joints and class pressure-temperature ratings are included in Sec. 10, Process Plant Piping. Control valves have their own standardized face-to-face dimensions that are governed by ISA Standards S75.03, 04, 12, 14, 15, 16, 20, and 22. Butterfly valves are also governed by API 609 and Manufacturers Standardization Society (MSS) SP-67 and 68. 

Figures 10-133 and 10-134 illustrate the wide variety of types and facings available. Though flanged joints consume a large volume of metal, precise machining is required only on the facing. Flanged joints do not impose severe diametral tolerances on the pipe. Careful alignment prior to assembly of flat-face and raised-face flanges is not required, and the necessary wrenches are far smaller than those for screwed assembly for the same size of pipe.

Threaded slip-on socket welding Lap joint Welding neck ANSIB16.1, screwed (125-lh)... 

Steel forged fittings with screwed ends may be installed without pipe dope in the threads and seal-welded (Fig. 10-130) to secure bubble-tight joints with a minimum of welders labor. They are not subject to deformation by pipe wrenches, and such couplings, bushings, and plugs are often used with the screwed fittings below. 

Screwed joints which are intended to be seal-welded shall be made lip without any thread compound. 

The heatable areas of the diyer are the vessel wall and the screw. The diyer makes maximum use of the product-heated areas—the filling volume of the vessel (up to the knuckle of the dished head) is the usable product loading. The top cover of the vessel is easily heated by either a half-pipe coil or heat tracing, which ensures that no vapor condensation will occur in the process area. In addition to the conical vessel heated area, heating the screw effectively increases the heat exchange area by 15-30 percent. This is accomphshed via rotary joints at the base of the screw. The screw can be neated with the same... 

Table 29.2 Recommended sizes of punched washers for hexagonal bolts and screws as in IS 2016 to make a good joint ...

Some of the more obvious sources of contamination of solvents arise from storage in metal drums and plastic containers, and from contact with grease and screw caps. Many solvents contain water. Others have traces of acidic materials such as hydrochloric acid in chloroform. In both cases this leads to corrosion of the drum and contamination of the solvent by traces of metal ions, especially Fe. Grease, for example on stopcocks of separating funnels and other apparatus, e.g. greased ground joints, is also likely to contaminate solvents during extractions and chemical manipulation. 

The values calculated using Eqs. (3-36) and (3-37) are only true for welded pipelines. Extension joints, fittings, and screwed or caulked joints can raise the longitudinal resistance of a pipeline considerably and therefore must be bridged over for cathodic protection. 

The special forms consist of the many types of anode which are used for protecting smaller containers. Boilers, heat exchangers and condensers belong to this group. Besides the rod anodes already mentioned with tube screw joints which can be screwed into the container from outside, there are also short and round anode supports as well as more or less flat ball segments which are bolted onto the protected surface with cast-on supports. These shapes are mostly manufactured from magnesium alloys. In addition, there are star-shaped or circular anodes for installation in condensers and pipes. The weight of these anodes lies between 0.1 and 1 kg. 

The connections were not made correctly. In particular, screwed joints were secured by only a few threads, different threads were combined, or gaskets were missing. 

The valve was screwed onto the pipeline, though the company s codes made it clear that only flanged or welded joints were allowed. 

The size and frequency of leaks can be reduced by using spiral-wound gaskets in place of compressed asbestos fiber ones. Screwed joints should not be used. 

In making up the field joint it is possible for the coupling to make up slightly on the mill end. This does not indicate that the coupling on the mill end is too loose, but simply that the field end has reached the tightness with which the coupling was screwed on at the mill. 

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