SAILENT TECHNICAL FEATURES

Work : Supply & Fixing of Cladding and Flashing Sheet in NTPC - Bongaigaon

Estimated Cost : Rs. 130.924 Lacs.

Completion period : 5 months

“Salient Technical Features of the “Supply & Fixing of Cladding and Flashing Sheet in NTPC - Bongaigaon” covered in NIT/IFB No 40033612 dated 10.03.2015 are mentioned below. These salient technical features are mentioned only to facilitate the prospective bidders to prima-facie understand the requirements under the tender and shall not in any way limit or alter the scope of work and technical features/ specification of Supply & Fixing of Cladding and Flashing Sheet in NTPC - Bongaigaon covered in the bidding documents. Detailed provisions in regard of scope of work and technical features/ specifications of Supply & Fixing of Cladding and Flashing Sheet in NTPC - Bongaigaon contained in the bidding documents shall be final and binding”.

SALIENT TECHNICAL FEATURES

a) The sheeting shall be fixed as per the working drawings. Sheets shall be supplied in required sizes (based on purlin spacing) according to the cutting schedule. Generally cutting of sheets shall not be permitted at site. Specific approval under exceptional circumstances shall be obtained before cutting of any sheet at site. Power tools shall be used for cutting. Cutting and trimming of small openings which were not finalised at the time of working drawings can be allowed at site. Wherever possible, site cut edges shall be concealed at laps or with flashing. Suitable steel members for stiffening shall be provided at the cut edges. No gas cutting shall be done on the sheet. If any sheet is found with gas cut mark, same shall stand rejected and shall be immediately replaced.

b) Distorted, blemished or water stained sheets shall not be used.

c) Before installing roofing/cladding, it shall be ensured that the supporting structure i.e. purlins/runners are in true planes, correctly placed and securely fixed.

d) Side and end laps of the sheets shall be made weather proof by securing them with the fasteners not less than 4.0mm dia with 2.0 mm thick neoprene washer and cap of matching colour. Maximum spacing of the fasteners not to exceed 500 mm.

e) Precautions shall be taken during the erection of roofing/ cladding to ensure that partially erected roofing/cladding and insulation (pending placing of external cladding sheet) are protected during inclement weather to prevent the ingress of water and damage at all times.

f) During erection of roofing/cladding, ladders shall not be leaned on any cladding without precautions being taken against damage.

g) The fasteners shall be installed by means of power tools and provided with neoprene seal.

h) Length of the sheet shall be such as to cover minimum 3 span purlin spacings.

i) Expansion joints shall be provided to take care of movements due to temperature variations.

j) The sheets shall be laid on the steel purlins/runner or scantlings to a true plane with the lines of profiles truly parallel to or normal to other sides of the area to be covered, unless otherwise required as in special shape.

k) Cladding erection for each elevation shall commence at the bottom and proceed towards the top, in order to ensure tight fitting laps.

l) The sheets shall be laid with a minimum overlap of 15 cm at the ends and side laps shall be of one trough length subject to a minimum of 50 mm, having a proper water tight arrangement. The minimum lap of sheets with ridges, hips and valleys shall be 15 cm measured at right angles to the line of the ridge, hip and valley respectively.

m) In case of insulated sheeting works, the insulation shall be provided.

n) In case double skin cladding, inner sheet and outer sheet can be directly fixed to the opposite faces of the sheeting runner totally concealing the supporting steel structure.

o) Crimping and curving wherever specified shall be provided over the profile sheet.