X cross-arm for transmission steel tower or poles
This photo refers to our X cross-arm for transmission steel tower or poles, their technical specification as follow:
General information:
1.1 X-arms shall be made out of 100 x 50 x 6 mm Channel for 11/22/33KV transmission tower or poles, even high voltage projects.
1.2 The cross arm shall be hot dipped galvanized generally conforming to Chinese standard or some international standard which client required.
1.3 The X-arm should not be welded/ jointed at any place except as specified.
1.4 The clamps for the X-arm shall be of G.I. & shall be hot dipped galvanized
1.5 The clamps shall be designed to fit for the specified projects.
Material and size:
1.1 The cross arms shall be of MS channel, which we adopt Chinese steel Q235B/
1.2 The cross arms shall have two holes of 22 mm diameter (for 11kV line) and 26 mm diameter (for 33kV line) for fixing of pin insulators. The center-to-centre distance between the holes shall be 1070 mm (for 11kV) and 1525 mm (for 33kV) and holes shall be in the middle of the top width of cross arm. Even we design for our client as per their requirements.
1.3 If required by the owner, holes of specified size and spacing shall also be provided for fixing of pole back clamp to suit the pole.
TESTS:
Our cross-arm tests shall be carried out in accordance with Chinese standard or some other standard which client required.
(a) Visual Check
(b) Verification of Component Rating
(c) Other Checks
i) Easy Accessibility and Maintenance
ii) Colour Coding provided by coloured tapes.
iii) zinc coating test
MEGATRO is a full service engineering company with a global reputation for delivering excellence and innovation in power transmission, transformation, distribution, and telecommunications systems. Our MEGATRO provide and design this type 110KV gantry type Single circuit tower mainly for our overseas client. Since 2004, MEGATRO focus mainly international market and had export many kind of transmission structures to overseas clients. MEGATRO has been manufacturing lattice transmission tower & tapered steel poles for lighting, traffic control, communication and utility applications. MEGATRO pioneered the development of transmission tower, telecom tower, substation, and other steel structure and was also at the forefront in the design of Transmission tower.
Over 10 years of experience and innovation in engineering, designing and building towers has evolved MEGATRO into its current form:
l Full Turn-Key provider including site acquisition, engineering services, manufacturing, field services-DAS, tech services, value added reseller and monitoring, maintenance and network ownership
l Specialize in developing supplying and building wireless and wired networks and in-building telecommunications systems, as well as energy infrastructure
l Single source from Design to System Integration
l Top quality, ISO 9001 registered
A complete selection of towers including self-support, lattice steel tower, monopoles and guyed towers, form custom-designed radar towers to broadcast towers and energy infrastructure. MEGATRO carries a variety of related products including fall protection, transmission lines, antennas, obstruction lights, and accessories, and other products if client need, MEGATRO also tailored product as per client condition.
MEGATRO mainly design all kinds of towers and posts for:
a. Telecoms
b. Power transmission
c. TV and Radio Broadcast
d. Roads and City Development
e. Wind energy solution
f. Steel structure and workshop
Our complete selection of towers includes:
a. Self-supporting
b. Monopoles
c. Guyed towers
d. Custom-designed radar towers
e. Broadcast towers
f. Power transmission
MEGATRO also designs and manufactures tower related products including:
a. Fall protection
b. Antenna brackets
c. Other accessories if needed by clients
Today, with over 10 years of experience and our commitment to excellence, MEGATRO remains an industry leader in the manufacture and design of steel tubular & angular & monopole structures for all Highway, Municipal, Custom, telecom, lighting and electric Utility applications. MEGATRO has a complete staff of professional engineering personnel trained in the PLS Pole program and three different manufacturing processes for producing steel towers, poles and other supports. We utilize the latest versions of PLS-CADD, PLS-POLE, TOWER, AutoCAD and other CAD software.
The structure shall be designed according to load combinations given as per IEC 61936-1 and as illustrated below:
Normal loads
1 Dead weight load
2 Tension load
3 Erection load
4 wind load
Exceptional loads
1 Switching forces
2 short-circuit forces
3 Loss of conductor tension
4 Earthquake forces
Moreover, MEGATRO is fully equipped and qualified to carry out Design Engineering services which includes:
√ Overhead Transmission line steel tower & Telecom steel tower
Basic Design and Analysis
√ Shop Erection Drawings
√ As-Built Drawings
MEGATRO performs in-house design activities specializing in electrical overhead transmission &telecom tower steel works, which include wind and earthquake loading, static analysis, stress analysis by finite element methods and fatigue. Our Engineering Department is boasting of highly qualified engineering who are conversant with international codes and standards. The work is carried out with extensive use of CAE/CAD via a large of computer network. The computer hardware & drafting software are liked to the CNC workshop equipment for downloading of information thereby eliminating error and saving valuable production time.
Besides, MEGATRO is one of the few manufactures who assemble a face of transmission tower. This attention to quality may not be the cheapest process but it does insure every tower meets our high standards of quality. And it helps to reduce on-site construction cost due to mismatched assemblies. After fabrication all transmission towers are delivered to the galvanizing facility to be Hot DIP Galvanized. Towers are processed through the facility by Caustic Cleaning, Pickling, and then Fluxing. These strict procedures insure years of maintenance free towers.
Other information:
Fabrication standard: Chinese Standard or other standard which client accepted
A) Dimension and tolerance for angle are according to GB/T1591-1994, similar to EN 10056-1/2
B) Hot dip galvanization in accordance with GB/T 13912-2002, which similar to ASTM A 123
C) The welding will be performance in accordance with AWS D1.1 or CWB standard
D) All fastener galvanization conform to ASTM A153 requirements.
Package: Both parties discuss before delivery
Port of Loading: Qingdao Port
Lead Time: One month or based on the customer's needs ( for time being our capacity about 5000 tons one month, and can meet client requirements)
Minimum order: 1 set
General Fabrication Requirements
Here is general fabrication requirements for our transmission tower; however, both parties must discuss all drawings and confirm all shop drawings, technical specification, and which standard to conform.
Before mass production, we must received all signed approved shop drawings and technical documents from our client.
Our Fabrication shall be in strict accordance with detail Drawings prepared by the Contractor and approved by the Engineer. Fabrication shall begin after the approval of the shop assembly and tests.
Shearing
Shearing and cutting shall be performed carefully and all portions of the work which will be exposed to view after completion shall be finished neatly. Manually guided cutting torches shall not be used.
All material over 13 (or 12) mm thick shall be cold sawn or machine flame cut.
Cropping or shearing shall be allowed for material thickness of 13 mm or less.
Flame cutting of high yield steel shall be preceded by a slight preheat operation by passing the cutting flame over the part to be cut.
All flame-cut edges shall be ground clean.
Bending
Bending shall be carried out in such a manner as to avoid indentation and surface damage. All bending over 5o, or high yield steel, shall be performed while the material is hot.
Welding
No welding shall be done unless prior approval has been obtained from the Engineer.
Welding shall not be allowed at tower attachment points for conductor, shield-wire, insulators or associated assemblies or brackets.
Sub-punching
All holes in structural steel less than 10 mm thickness may be punched to full size unless otherwise noted on the approved Drawings. Holes shown on the Drawings as drilled holes and all holes in structural steel 10 mm or more in thickness and tension members of cross-arms shall be drilled or sub-punched and reamed.
All holes shall be clean cut and without torn or ragged edges. All burrs resulting from reaming or drilling shall be removed. All holes shall be cylindrical and perpendicular to the member.
Where necessary to avoid distortion of the holes, holes close to the points of bends shall be made after bending.
Punching
For punching to full size, the diameter of the punch shall be 1.0 mm larger than the nominal diameter of the bolt, and the diameter of the die shall not be more than 1.5mm larger than the diameter of the punch. For sub-punching, the diameter of the punch shall be 4 mm smaller than the nominal diameter of the bolt, and the diameter of the die shall be not more than 2 mm larger than the diameter of the punch. Sub-punching for reamed work shall be such that after reaming no punch surface shall appear in the periphery of the hole.
Hole Size
Where holes are reamed or drilled, the diameter of the finished hole shall be not greater than the nominal diameter of the bolt plus 1.0 mm.
Accuracy
All holes shall be spaced accurately in accordance with the Drawings and shall be located on the gauge lines.
The maximum allowable variation in hole spacing from that indicated on the Drawings for all bolt holes shall be 0.8 mm.
Fabrication Tolerances
A specification for tolerances shall be submitted for approval by the Engineer prior to commencement of fabrication.
Bolt List
A complete list of bolts showing their lengths and the members, which they are to connect shall be given on the erection diagrams.
Locking Devices
Locking devices for tower bolts will not be required, but point punching shall be performed.
Anti-theft Fasteners
Appropriate anti-theft fasteners for example Huck-bolting shall be applied on all the towers up to the level of anti-climbing devices, to prevent theft of tower members.
Piece Marks
All pieces shall be stamped before galvanizing with the piece marks shown on the erection Drawings, with the marking not less than 20 mm high placed in the same relative location on all pieces. The marking shall be plainly visible after galvanizing.
Galvanizing
All material shall be hot-dip galvanized after fabrication in accordance with the latest revision of GB/T 13912-2002 or ASTM Specification A 123.
Material that has been rejected because of bare spots or other coating defects shall either be stripped and re-galvanized, or the uncoated areas shall be recoated by an approved method.
All plates and shapes which have been warped by the galvanizing process shall be straightened by being re-rolled or pressed. The material shall not be hammered or otherwise straightened in a manner that will injure the protective coating.
Approval shall be secured from the Engineer if galvanizing is done outside of the Contractor's plant.
All galvanized steelwork shall be protected against white storage stain by using an approved dichromate solution treatment immediately following galvanizing.
APPLICABLE STANDARD AND CODES
All towers manufactured and design shall be generally in accordance with latest revision of the following standards except where specifically directed otherwise.
General
IEC 60826 - Design criteria of overhead lines
IEC 60652 - Loading tests on overhead line structures
ISO 1459 - Metallic coatings - Protection against corrosion by Hot Dip Galvanizing
ISO 1461 - Hot dip galvanized coatings on fabricated iron and steel articles
ISO 12944 - Paint coatings, corrosion protection, and structural steelwork
ISO 898-1 - Mechanical properties of fasteners. Part 1-Bolts, Screws and studs
ISO 630 - Structural Steels - plates, wide flats, bars, sections and profiles
ISO 657 - Hot rolled structural steel plates tolerances on dimensions and shape
ISO 7411 - Hexagon Bolts for high strength structural bolting with large width across flats
ISO 657-5 - Hot rolled Structural Steel Sections equal and unequal leg angles
ISO 7452 - Hot rolled structural steel plates tolerances on dimensions and shape
BS EN 50341-1 - Overhead electrical lines exceeding AC 45kV -General Requirements
BS 8004 - Code of Practice for Foundations
BS 8110 - Structural use of concrete
ANSI10-97 - Design of latticed steel transmission structures
IEC 60050 (151) International Electro-technical Vocabulary
Part 51 Electrical and Magnetic Devices
IEC 60050 (601) Chapter 601: Generation, transmission and distribution of electricity-General
IEC 60050 (601) Chapter 601: Generation, transmission and distribution of electricity-Operation
IEC 60059 IEC standard current ratings
Chinese Standard
| No |
Code |
DESCRIPTION |
| 1 |
GB/T2694-2003 |
Power Transmission line Steel tower - Technical requirements for manufacturing |
| 2 |
JGJ81-2002 |
Technical specification for welding for steel structure of building |
| 3 |
GB9787-88 |
Measuring and allowable tolerance for hot-rolled equal angle |
| 4 |
GB709-88 |
Measuring and allowable tolerance for hot-rolled plate and strip |
| 5 |
GB/T699-1999 |
Quality Carbon Structural Steel |
| 6 |
GB/T1591-1994 |
Low alloy high strength structural Steel |
| 7 |
GB700-88 |
Carbon Structural Steel |
| 8 |
GB222-84 |
Method of sampling steel for determination of chemical composition and permissible variations |
| 9 |
GB/T228-2002 |
Method for Tensile testing of metals |
| 10 |
GB/T232-1999 |
Method for Bending test of metals |
| 11 |
GB/T5117-1995 |
Carbon Welding Rod |
| 12 |
GB/T5118-1995 |
Low Alloy Welding Rod |
| 13 |
GB/T8110-1995 |
Welding wires for gas shielding arc welding of carbon and low alloy steels |
| 14 |
GB/T10045-2001 |
Carbon steel flux cored electrodes for arc welding |
| 15 |
JB/T7949-1999 |
Weld outer dimensions for steel construction |
| 16 |
GB50205-2001 |
Test Standard for Acceptance of Steel Structure |
| 17 |
GB/T470-1997 |
Zinc Ingot |
| 18 |
GB3098.1-2000 |
Mechanical properties of fasteners-Part 1:Bolts, screws and studs |
| 19 |
GB3098.2-2000 |
Mechanical properties of fasteners-Part2: Nuts, and thread |
| 20 |
GB3098.3-2000 |
Mechanical properties of fasteners-Part3: Fastening screw |
| 21 |
GB/T5780-2000 |
Helical Bolts Grade C |
| 22 |
GB/T41-2000 |
Helical Nuts Grade C |
| 23 |
GB/T90-2002 |
Flat Washer Grade C |
| 24 |
GB/T13912-2002 |
Metal Coating, Technical Requirement and Test Method for Hot-dip galvanized Metal Parts |
American Standards:
| Standard |
Description |
| ASTM A6/A6M |
Standard specification for general requirements for rolled structural steel bars, plates, and sheet piling. |
| ASTM - 6 |
- General Requirements for delivery of Rolled Steel Plates, Shapes, sheet Piling Bars for structural used |
| ASTM A36/A36-M-97a |
Standard specification for Carbon structural steel |
| ASTM A123 / A123M-02 |
Standard specification for Zinc (Hot-Dip Galvanized) Coatings on iron and steel products |
| ASTM A143 / A143M-03 |
Standard Practise for Safeguarding Against Embitterment of Hot-Dip Galvanized Structural Steel Products and Procedure for Detecting Embitterment |
| ASTM A153/ A153M-05 |
Standard specification for zinc coating (Hot-Dip) on iron and steel hardware |
| ASTM A - 194 |
- Grade for bolt |
| ASTM A239 |
Standard practice for locating the thinnest spot in a zinc (Galvanized) Coating on Iron or Steel Articles |
| ASTM A242 |
Standard specification for High-Strength Low-Alloy Structural steel |
| ASTM A307 |
Standard Specification for Carbon Steel Bolts and Studs, 60000 PSI Tensile strength |
| ASTM A370-06 |
Standard Test Methods and Definitions for Mechanical Testing of Steel Products |
| ASTM A325 |
Standard Specification for structural bolts, steel, Heat treated 120/105 ksi minimum tensile strength |
| ASTM A-325 or A-354 |
- Galvanized hexagonal head of connection bolt |
| ASTM A325-97 |
Standard Specification for High-strength Bolts for structural steel Joints |
| ASTM A384 / A384M-02 |
Standard Practise for Safeguarding Against Warpage and Distortion During Hot-Dip Galvanizing of Steel Assemblies. |
| ASTM A394-93 |
Standard Specification for steel Transmission Tower, Bolts, Zinc Coated and Bare |
| ASTMA - 563 |
- Class and size of nuts |
| ASTMA - 572 |
- Chemical composition of steel |
| ASTM A572/A572-97c |
Standard specification for High-Strength Low-Alloy Columbium-Vanadium Structural steel |
| ASTMA - 615 |
- The anchor bolt material |
| ASTM A673 / A673M-07 |
Standard Specification for Sampling Procedure for Impact Testing of Structural Steel |
| ASTM B201 |
Standard practice for testing Chromatic coating on Zinc and Cadmium surfaces |
| ASTM E94-93 |
Standard Guide for Radiographic Testing |
| ASTM E 709-95 |
Standard Guide for Magnetic Particle Examination |
| ASCE Manual 72 |
- Load testing a simple structure |
| ASCE 10-97 |
Standard Design of latticed steel transmission structures |
| AWS D1.1 |
American Welding Society D1,1/D1,1M structural Welding code- Steel |
| ANSI B-182-2 |
Bolts, nuts and washers dimensions |
DIN VDE 0101 - Isokeraunic Level
VDE 0201 - Climatic and environmental conditions
CVDE 0210 - Minimum safety factors under simultaneous working loads
ISO R898 Mechanical Properties of Fasteners
BS EN ISO 1461:1991 - High dip galvanized coatings on fabricated iron and steel articles. Specifications and standards
A) BS 5950: Welding Terms And Symbols
B) BS 729: Hot - Dip Galvanised Coating On Iron And Steel Articles
C) BS 2901: Filler Rods And Wires For Gas Shielded Arc Welding: Part 1 Ferritic Steels
D) BS 3692: ISO Metric Precision Hexagon Bolts, Screws And Nuts
E) BS 4360: Weldable Structural Steel
F ) BS 5135: Metal - Arc Welding Of Carbon And Carbon Manganese Steel
G) BS 5950: Part 1: Code Of Practice For Loading Latticed Tower & Masts
Part 2: Guide To The Background And Use Of Part 1"Code OF Practice For Loading"
Part 3: Strength Assessment of Members
H) DD 133 (1986): Code Of Practice For Loading Latticed Tower & Masts
I) BS 4592 (1987): Part 2: Specification For Expanded Metal Grating Panels
J) BS 4592 (1977): Code Of Practice For Protective Coating Of Iron And Steel Structure Against Corrosion
K) BS 4190: Bracing & Flanged Bolts
L) BS 4190: Rolled Steel sections, Flats & Plates
If any special requirement, we can design and discuss with client.
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