Process Vessels

Vessels: Insulation Product Selector

Heating Systems
Boiler Rooms
Plant Rooms

Vessels can include large and small rectangular, cylindrical and irregular pieces of equipment, high towers for chemical process plant, large storage tanks and spheres as well as boilers and steam turbines. In selecting the most suitable product, the operating temperature, degree of insulation efficiency and the robustness of insulation must all be taken into consideration. Generally the higher the temperature, the higher the density required. However, it may be prudent to select a density of slab higher than that necessary for the temperature when a more robust insulant is required to support the covering and other loads which may at times be imposed, such as foot traffic on the surface of large vessels.

For cylindrical vessels up to 1120mm Knauf Insulation recommend they are insulated as pipes. For vessels between 1120mm and 3500mm in diameter, Knauf Insulation recommend Crown Universal Slabs with a density of not more than 32kg/m³ or Rocksilk Universal Slabs of density 45kg/m³. These slabs are sufficiently flexible for this curvature. For cylindrical vessels over 3500mm in diameter, any density of Crown Universal Slab or Rocksilk Universal Slab may be used.

Typical Specification Clauses for Vessels

VC1 Application using Crown and Rocksilk Universal Slabs

Cylindrical vessels shall be insulated with Crown Universal Slabs/Rocksilk Universal Slabs ......mm thick, firmly secured to the vessel with metal bands, adhesive or a combination of both. The metal bands should not be over tensioned so as to significantly reduce the thickness of the insulation. On vertical surfaces, circumferential support rings shall be fitted and spaced apart at distances which will provide adequate support according to the weight of the insulation. The support rings shall protrude from the vessel to a maximum distance of 10mm less than the thickness of the insulation. All joints must be well butted together and vertical joints staggered on adjacent courses. In multi-layer applications, all joints shall be staggered.

The insulation may be fixed to domed ends by impaling over pins and secured with spring washers or forked pins welded to the vessel. In either case, the outer ends of the pins should be depressed below the surface of the insulation to prevent heat being transmitted direct to the covering.

Note: Vessels operating at sub-ambient temperatures must have an adequate continuous vapour seal applied over the insulation and fixings.

VC2 Application using Rocksilk Mattress

Vessels shall be insulated with Rocksilk Mattress, Grade ....., .....mm thick. Mattresses to be closely butted together and the edges of the outer layer of wire netting laced together with wire. Joints in multiple layers should be staggered. The mattress to be impaled over pins and secured with 50mm flat square washers and capped with spring clip washers.

Metal pins or forked studs to be welded/screwed to the surface of the vessel at the following pitches:

vertical surfaces at an approximate square pitch of 450mm
upward facing surfaces 600mm
overhanging or downward facing surfaces 300mm.

When using pins with spring clip washers the length of the pin to be 12mm shorter than the thickness of the insulation to avoid hot spots on the cladding.

Forked studs to be longer than the insulation thickness and turned back and recessed into the insulation by approximately 10mm.

VC3 Sheet metal cladding for internal or external use

The application of sheet metal cladding must meet certain requirements which are set out below but depending on size, location, environment etc a specific design may be necessary.

Special kinds of studs which reduce heat conduction may have to be provided, welded to the vessel surface or other attachments used. Alternatively a self supporting framework may be installed. Flat or profiled sheet may be used.

All circumferential joints must be overlapped weatherwise in order to shed water, and secured with self tapping screws or easy fix rivets. Where necessary, joints should be sealed with a suitable sealant to prevent the ingress of water or contaminating fluids. On large vessels certain overlaps should be designed to provide for expansion.

VR1 Rectangular vessels insulated with Crown/Rocksilk Universal Slabs

Rectangular vessels shall be insulated with Crown Universal Slabs/Rocksilk Universal Slabs, Type ....., .....mm thick, secured to the surface with suitable adhesive. The adhesive to be applied to cover the entire surface (it is important to follow the manufacturer’s instructions).

Alternatively, the insulation may be impaled over pins fixed to the surface of the vessel at the following pitches:

vertical surfaces at an approximate square pitch of 450mm
upward facing surfaces 600mm
overhanging or downward facing surfaces 300mm

Location of pins should be arranged so that there is a pin not more than 50mm from each corner of the slab.

All joints should be closely butted together. Vertical joints (and in multi-layer applications, all joints) must be staggered and at corners, adjacent slabs must be overlapped to the thickness of the insulation.

When using pins with spring clip washers the length of the pin to be 10mm shorter than the thickness of the insulation to avoid hot spots on the cladding.

VR2 Rectangular vessels insulated with Rocksilk Mattress

Rectangular vessels shall be insulated with Rocksilk Mattress, Grade ....., .....mm thick. Mattresses to be closely butted together and the edges of the outer layer of wire netting laced together with wire. Joints in multiple layers should be staggered. Care must be taken to maintain insulation thickness around the corners. The mattress to be impaled over pins and secured with 50mm flat square washers and capped with spring clip washers.

Metal pins or forked studs to be welded/screwed to the surface of the vessel at the following pitches:

vertical surfaces at an approximate square pitch of 450mm
upward facing surfaces 600mm
overhanging or downward facing surfaces 300mm.

VR3 Sheet metal cladding

The application of sheet metal cladding must meet certain requirements which are set out below but depending on size, location, environment etc a specific design may be necessary.