33kv 11m 12m steel utility pole, class 4 , The directly buried type
These specifications cover the design, engineering, manufacture,
assembly, testing at manufacturer's works before dispatch of steel
poles, cross arm assemblies, guy sets, danger plates, GI spike
earthing sets for 33kV Single pole line, Suspension and Tension
Fittings suitable for AAC Conductor for use on 3 phase, 50 Hz,
solidly earthed 33kV Overhead lines.
- The design and workmanship shall be in accordance with the best
engineering practices to ensure satisfactory performance throughout
the service life.
- Any material and equipment not specifically stated in this
specification but which are necessary for satisfactory operation of
the equipment shall be deemed to be included unless specifically
excluded and shall be supplied without any extra cost. Components
having identical rating shall be interchangeable. The bidder has to
furnish the testing facilities available at the manufacturer’s
The steel poles, cross arm assemblies, cross brace assemblies and
pole guard arms, guy sets, earthing sets etc. shall conform to the
relevant IEC standards and any other equivalent neutrally
acceptable International Standards (as amended upto date) mentioned
below shall be applicable to the materials and processes used in
the manufacturing of these equipment:
Hot-rolled steel sheet in coils of higher yield strength with
improved formability and heavy thickness for cold forming
BS 3288 : Part 1: 2018
Insulator and conductor fittings for overhead power lines.
Performance and general requirements
Fasteners — Hot dip galvanized
ASTM E350 - 18
Standard Test Methods for Chemical Analysis
Specifications For Rolling And Cutting Tolerances For Hot-Rolled
|ISO 12944-4:2017||Paints & Varnishes|
|ASTM A123||Recommended Practice for Hot Dip Galvanizing of Iron and Steel
|ASTM A123||Method of Testing Uniformity of Coating of Zinc;|
|ISO 1461:2009(en)||Hot-Dipped Galvanized Coatings on Round Steel Wires|
|IEC 60335-2-71||Specification For Poultry Incubators|
|ASTM A90||Determination Of Mass Of Zinc Coating On Zinc Coated Iron And Steel
|IEC 60120||Dimensions of ball and socket couplings of string insulator units|
Locking devices for ball and socket couplings of string insulator
- Dimensions and tests
|IEC 61109||Insulators for overhead lines- Composite suspension & tension
Insulators for A.C. systems with a nominal voltage greater than
1000V- definitions, test methods and acceptance criteria.|
|NFC 33-040||Suspension Equipment|
|NFC 33-041||Anchoring Devices|
Whenever there is a difference in the Standards the most stringent
criteria shall apply.
3.0 MATERIALS, CONSTRUCTIONAL DETAILS AND WORKMANSHIP
- Materials used in the manufacture of all the equipment shall be new
and best quality and class most suitable for performance under the
- Steel used for manufacture of various equipment shall be in
conformity with the general requirements relating to the supply of
materials laid done in relevant international standards.
- The material analyzed in accordance with ISO 13520:2015 or other
relevant international standard shall not show sulphur and
phosphorous contents of more than 0.060% each.
- Equipment shall be well-finished, clean and free from harmful
surface defects. Ends of steel poles, angle sections etc. shall be
cut square and shall be straight.
- The bolts, nuts & pack washers and guy wire strand & cross
arm guard wire shall be hot dip galvanized as per ISO 1461:2009(en)
or other relevant international standards. The quality of zinc
shall be at least Zn 98 grade specified in ISO 752:2004. The zinc
coating shall be adherent, smooth, reasonably bright, continuous
and free from such imperfections and flux, ash and dross,
inclusions, flake and black spot, pimples, lumpiness and runs.
- The steel poles shall be hot dip galvanized with minimum 125 micron
thickness of zinc coating and steel base plates with minimum 125
micron thickness of zinc coating generally as per ASTM A123 and
tested as per relevant international standards..
- The articles shall withstand minimum 4 dips of one minute duration.
The uniformity of galvanized coating shall be determined by the
preece test as prescribed in ASTM A123.
- Suspension and Tension Fittings shall be made of Aluminum Alloy and
all nuts and bolts shall be made of hot dip galvanized steel with
minimum thickness of zinc coating of 85 micron as per ISO
10684:2004(en) Part XIII or other relevant international standards.
4.0 THE SPECIFIC TECHNICAL REQUIREMENTS OF VARIOUS EQUIPMENTS
4.1 Steel Poles
The purchaser may at its discretion furnish the design and
fabrication data of one or more types of poles necessary for
fabrication and testing of poles by the supplier or alternatively
may ask the bidder to work out the optimum designs of poles and in
that case submit detailed design calculations on ‘excel format’ for
check and review by Employer.
Design of Poles shall be worked out and checked preferably as per
ASCE Manual- 72 / SEI - 48- 05 or other relevant international
standards. Poles shall be pre-drilled and supplied complete with
pole top cap and base plate.
4.1.1 Specific Constructional Requirement
188.8.131.52 Poles shall be designed to withstand the worst possible
combination of simultaneous loading of
- Lateral loads consisting of wind forces on conductors corresponding
to wind spans, wind force on insulators, wind force on pole and
maximum conductor tension.
- Vertical loads consisting of pole self-weight, weights of
conductors, insulators, cross-arm, additional equipment, lineman
and compressive force due to reaction of stays wherever applicable.
184.108.40.206 Steel poles for HV (33 kV), HV / LV mixed shall be worked
out for the following types and applications:
- Contractor shall submit the detailed design & drawing of pole
for each above said 33kV Transmission line for approval of Client
and sample drawing showing dimension & configuration are
- Poles shall satisfy the dimensional length and pole top loading
requirements as per the design parameters listed in this
specification. The dimensions across flats for top and bottom for
all poles are listed in this specification/drawings as a preferred
design to utilize one dimension for each type of pole length in so
far as design & working load criteria is met.
220.127.116.11 Working Load
Working Load of a pole specified herein and defined as the load
which when applied at 250 mm below top will induce the maximum
permissible stress in the pole, shall be marked on each pole.
- The standard poles shall be suitable for the specified applications
based on the design parameters given in Table 2, 3 & 4.
- A through hole of 14 mm diameter shall be provided in each pole at
a height of 300 mm above the planting depth for earthing. The
location of hole at a height of 300 mm shall be got approved from
the Employer before manufacturing of the poles.
18.104.22.168 Base Plates
All poles shall be placed during erection on M-20, PCC pad of
minimum thickness 75 mm and overall dimensions about 150 mm more
than outside bottom dimension of the pole.
Alternatively; poles shall be supplied with separate square steel
base plate fabricated from steel as per relevant Standards. Min.
thickness of base plates shall not be less than 6 mm. Design
calculations of thickness of steel base plates shall be submitted
for check and review by Employer.
Poles for small angle locations (0 - 30°) shall be self-supporting.
However; the poles for larger angle and terminal locations in
un-inhabited areas can be provided with Anchor Guys placed the
direction of the bi-sector of the angle at angle locations or
length wise at the terminal locations. In the inhabited areas guys
are not allowed; but Struts or two poles mechanically secured
together can be deployed.
22.214.171.124 Design Parameters and Factor of Safety
|Wind pressure (N/m2)||On pole||1200|
|On conductors at 10°C||600|
Factor of Safety
|Conductor minimum breaking strength||3.0|
|Planting Depth (m)||1.6|
|Allowable Deflection at Pole Top||5% of expose length|
|Minimum Breaking Load||101kN|
|Max. Tension||90% of min. breaking load|
|Min. angle to the pole||37°|
The tolerance on the length shall be as follows:
|i.||- Length of any section||+ 40 mm|
- Overall length of pole
|+ 25 mm|
The finished pole shall not be out of straightness by more than
1/600 of its length.
The rolling and cutting tolerance for hot rolled steel products
shall be in accordance with relevant international standards.