III. The construction of pre-insulation pipe.

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The Process of construction:
Equipment and pipe	The installation of support	Clean, test pressure and inspect
Resistant to corrosion	Inner insulation layer	Outer insulation layer
Damp resistant layer	Inspection	Protection layer
Inspection	Check and accept

• The equipment and pipe which need insulation layer should be inspected and approved up to their standard, which follows their working procedure before construction.
• The accessories on the equipment’s frame or pipeline such as bearing, trunnion, instruments, base, bracket and hanger, which should be cold insulated for no less than 4 times the thickness of the pipes length to be able to lay out the pipe support.
• When the thickness of cold insulation is larger than 80mm, it should be constructed by delaminating. The thickness of de-lamination used should be near the layer of cold insulation that is symmetrical and continuous. There should be no absence between the layers. The surface and joints of pipes should be neatly constructed.
• The gap in the joint should be firmly handled, the gap of cold insulation should be less than 2mm, and fill the gaps with the mixture of phenolic foam and phenolic resin.
• The damp resistant layer made of phenolic fiberglass plastic can be used as a protection layer directly. When used for fireproofing building’s mastic’ it should be used with sheet metal as a protective layer.

The construction of insulation layer

The main specification for the insulation layer that is made of phenolic foam, are as follows:

Phenolic foam	UNIT	SPECIFICATION
Density	kg/m3	40
Conductivity	w/m.k	0.020
Durability of heat	°C	150
Durability of cold	°C	-250
Adhesive strength	KN	135
Compressive strength	Mpa	0.2
Absorption rate	(v/v)%	1.9

The insulation layer of strait pipe and elbow:

• Fix the support and anchor before laying the insulation layer, the distance and width should follow the construction requirement.
• The length of rigid phenolic foam plastic should be 900-1000mm; its inner diameter should be a bit larger than outer diameter of pipe, it’s normally comprised by 2 or more pieces of insulation layer.
• During installation of the first and second layer, the phenolic foam should be tightened, compact and packed by cellophane tape. If there’s nick on the pipe, it should be filled before installation.

The elbow normally is cut to 45° slot for butt joint or cut to small taper for installation (see below):

click to enlarge	click to enlarge

click to enlarge	click to enlarge

The insulation layer should apply to the injecting structure construction methods:

1) the valve, flange, elbow of pipe and other special shapes insulation, should apply phenolic foam as filler for construction (which also can use polyurethane)

Follow the operation and installation manual below:

• Use phenolic foam to enclose a dies cavity, fix the interface by glue or cellophane tape.
• The specification and dimension of mold should be according to the out dimension and insulation thickness of valve, flange, elbow and other different shape objects.
• The collocation of phenolic foam filler: According to the proportion of phenolic fiberglass reinforced plastic resin, curing agent and phenolic foam powder to mix into loose powder form (which is a wet in texture)
• Calculate the volume of the rest dies cavity, then follow the above ways to fill the filler, to make the filler be solid and even, then smooth the surface.
• Cover the surface by a phenolic foam panel, and then seal it using an adhesive
  

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