Polyethylene sleeve

Although iron pipes suffer from the same corrosion risk as steel pipelines, associated with the generation of a galvanic cell with a small anode and a large cathode, the risk is mitigated for iron pipelines because the electrical continuity is broken at every pipe joint. For this reason long-line currents are uncommon in iron lines and cathodic protection is rarely necessary. It also accounts for the ability to protect iron lines by the application of nonadherent polyethylene sleeving . 

Weld joints may be coated in the field with FBE powder, utilising a portable blast cleaning/induction heating and powder application system. Alternatively joints may be provided with self-adhesive laminate tapes or heat-shrink crosslinked polyethylene sleeves. 

Repairs to the coating are made with either hot-melt polyethylene sticks or polyethylene sheet patches with mastic profiling compounds for small damaged areas. Large repair areas are best treated as for field weld joint coating, where either heat-shrink crosslinked polyethylene sleeves or cold-applied self-adhesive laminate tapes are employed. 

The microalgae are cultured in bioreactors under solar or artiflcial light in the presence of carbon dioxide and salts. The bioreactors may be closed systems made of polyethylene sleeves rather than open pools. Optimal conditions for pigment production are low to medium light intensity and medium temperatures (20 to 30°C). Pigment extraction is achieved by cell breakage, extraction into water or buffered solution, and centrifugation to separate out the filtrate. The filtrate may then be partly purified and sterilized by microfiltration and spray dried or lyophilized. 

Hot-melt adhesives based on bitumen show good adhesion to many materials and are resistant to water and weather. One important commercial use in which plastics are involved is the construction of road signs and other street furniture, where these adhesives are used to bond polyethylene sleeves to steel tubes. 

Sivaramakrishnan a/. (1989) described BST matrix implants consisting of either BST/ethyl cellulose or BST/poly(lactic acid) (Hi2700) contained within microporous polyethylene sleeves (average pore size 30-70 m). The in vitro dissolution studies showed significant initial release from uncoated tablets (70% cumulative release in the first 4 days to a total of 80% in 8 days) the coated tablets had sustained release over 14 days with 35% cumulative release over that time. 

Thin coatings consist of paints and varnishes, which are applied as liquids or powdered resin with a thickness of about 0.5 mm [e.g., epoxy resin (EP) [2]]. Typical thick coatings are bituminous materials [3] and polyolefins [e.g., polyethylene (PE) [4]], thick coating resin combinations [e.g., EP tar and polyurethane (PUR) tar [2]] as well as heat-shrinkable sleeves and tape systems [5]. 

Polyethylene loose sleeving AWWA/ANSI C105 BS 6076 By hand in the field 0-2-0-25 Very economical and lightweight. Most commonly utilised over zinc sprayed ductile iron pipes. Will not allow application of effective cathodic protection. May not arrest all corrosion. 

Polyethylene separators offer the best balanced property spectrum excellent mechanical and chemical stability as well as good values for acid availability and electrical resistance have established their breakthrough to be the leading traction battery separator. Rubber separators, phenolic resin-resorcinol separators, and mi-croporous PVC separators are more difficult to handle than polyethylene separators their lack of flexibility does not allow folding into sleeves or use in a meandering assembly in addition they are more expensive. 

A 5-1. three-necked flask is fitted with a stirrer (which may be of the glass-sleeve type lubricated with paraffin oil, or a mercury-sealed Hirshberg stirrer), an efficient condenser fitted with a calcium chloride drying tube, and a gas inlet tube. The gas inlet tube is connected with polyethylene tubing through a small bubble counter containing a nonvolatile hydrocarbon to the cylinder of boron trichloride. 

Much work has been done within the framework of the international programme JUPAC by 14 laboratories of different companies to reveal a characteristic of polymer material correlating with specific features of its molding into sleeve film67). The studies were conducted with two samples of low-density polyethylene and two samples of high-density polyethylene. The samples had minor differences in molecular-weight distribution and ramification characterized by the content of different side branches. 

Hot-melt spray adhesives will bond successfully carpets, fabrics, laminating panels, metals (both painted and unpainted), and both polyethylene and polypropylene film and sheet. Two important commercial uses at the time of writing are bonding sleeves of low-density polyethylene to ductile iron pipes and bonding sound-deadening materials and carpets to the floors of motor cars. 

Extruded polyethylene. Extruded polyethylene has been in general use for 25 y. The polyethylene is applied by either a forward extrusion or a side extrusion process. The forward extrusion is presently limited to 24 in. (610 mm) outside diameter pipe. The side extrusion can be used for sizes up to -120 in. (3,050 mm). Extrusions are usually shop-applied but can be applied at the railhead if economics permit. In addition to excellent temperature (-40 to 150°F (-40 to 66° CJ) and water resistance, the extruded polyethylene coatings exhibit excellent resistance to disbonding and soil stresses. The commonly used 50 mil (1.3 mm) thickness offers excellent resistance to handling damage. The bonding problems with early applications of the side extrusion appear to be solved. Field joints are often made with heat-shrinkable sleeves. 

Okopack Film S is semi-transparent with properties similar to polyethylene. Okopack C and S can be used for production of flat films, sleeve films and bags and sacks, which can be used for fruit and vegetable packaging. 

Of special interest on multiple-spout conveyor-equipped fluidizers and on certain types of screw and belt filling machines is a combination operator s seat, bag rest, and tuck-in-sleeve work aid. This device places the operator in an optimum work position after filling, to allow easy and positive tucking of the sleeve. Extensive use of the polyethylene film internal sleeve, however, has reduced the significance of die tuck-in-sleeve feature. Several types of heat-sealable valve-bag sleeves are available, as is equipment for closing them automatically. These are used when even slight leakage of product from an internal sleeve bag is unacceptable. 

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