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      Welcom to QINGDAO MEGATRO HOLDING CO.,LIMITED

      FAQ

      FAQ

      • Question31. How do I evaluate correctness of design of my tower?

        Following inputs are required from user.
        a) Physical size, weight and size of antenna /cross-arm to be fixed.
        b) Heights and orientation of these antennas/cross-arm on the tower.
        c) Wind velocity for which tower is to be designed. Wind velocity requirement is determined by location of tower.
        d) Twist and sway permitted by the communication system/conductor &earth wire operating on the tower.
        e) Codes to be followed for design. Normally all MEGATRO designs, when checked by third parties are approved without any modifications, however if so desired by the customer, MEGATRO will produce a certificate from professionally acceptable Government design institute confirming the correctness of design against desired parameters.

      • Question32. How much safety is built into design of my tower?

        Different suppliers of towers adopt different design philosophies. In LRFD method of design the material is subjected to 100% yield stress. The multiplying safety factors for load and resistance are to be decided by the designer. In working stress method, the permissible stress is provided by code itself. It is possible in LRFD method to adopt a lower multiplying factor and arrive at a light weight tower. Working stress method on other hand does not leave that option open and normally results in heavier and safer tower.

      • Question33. How do I evaluate the quality of fabrication of tower?

        If tower members are properly fabricated, then they will not require widening, elongation etc. of holes on site during erection. MEGATRO is proud of its quality of fabrication. Cutting of members, widening or elongation of holes on site by the erection crew is never required with MEGATRO fabricated tower materials.

      • Question34. Which quality of steel should we specify for our tower? What standard should be used?

        Quality of steel consists of quantitative measures of several different properties / characteristics of steel. End use of steel decides, which property of steel is of importance or relevance for that application. For example, if a chemical reactor is to be fabricated, chemical resistance is of relevance. If steel is to be used as a cutting tool on lathe, then its mechanical strength at high temperature, involved in cutting, is relevant. In a communication or transmission tower, which has been designed to operate within elastic region of steel behavior, the most relevant property of steel is a) Yield Strength of steel. Other properties of lesser importance are
        a) Ultimate tensile strength
        b) Percent Elongation
        c) Chemical Composition
        d) Weld ability etc. Each country, depending on
        a) Availability of raw materials within that country
        b) Availability of production facilities/technologies
        c) End use of steel has evolved several standards of steel for each application /end use. Manufacturers of towers everywhere, tend to specify standards of their own country. However, to meet the challenge generated by the situation that manufacturers and end users are from different countries, "International Organization for Standardization" Geneve, Switzerland has been formed.
        Certain standards have been finalized by this organization in consultation with member countries. Standard ISO 630, for structural steels, is one of such International Standards.
        Steel property can be tabulated at the end as Table 1 and Table 2 are follow:
        a) Relevant properties of tower steel for various standards.
        b) Range of values for Standards of different countries. As several grades of steel are available, any one grade could be chosen for use in the manufacture of tower. However, the properties of only the chosen grade must be used in the design process. As any grade of steel can be tailored by design process to get the required performance and strength of tower , objective of " Grade Selection Process " is only
        a) to keep the total cost minimum for the required performance of tower.
        b) To ensure easy availability of desired sections in selected grade of steel If higher value of "Yield Strength" is chosen, then lesser quantity of steel will be required. If lower value of "Yield Strength "is chosen, then comparatively larger weight of steel will be required. Higher value of "Yield Strength" is likely to result in lesser number of gussets, lesser number of holes, faster production and therefore lesser production cost. But the raw material cost of "High Yield Strength" is likely to be high. Availability is also expected to be less, resulting in longer delivery periods. Inspection requirements for high yield strength steel, will go up, because strength of structure will be impaired, if "Yield Strength" is not equal to design value.
        b) To ensure easy availability of desired sections in selected grade of steel If higher value of "Yield Strength" is chosen, then lesser quantity of steel will be required. If lower value of "Yield Strength "is chosen, then comparatively larger weight of steel will be required. Higher value of "Yield Strength" is likely to result in lesser number of gussets, lesser number of holes, faster production and therefore lesser production cost. But the raw material cost of "High Yield Strength" is likely to be high. Availability is also expected to be less, resulting in longer delivery periods. Inspection requirements for high yield strength steel, will go up, because strength of structure will be impaired, if "Yield Strength" is not equal to design value.
        Weldability of steels above yield strength of 355 Mpa is questionable. Therefore if welding has been planned in the manufacturing process, it is Desirable to keep the yield strength below 355Mpa. The final decision of selection of grade of steel is governed by
        a) Availability of that grade in that country
        b) Cost of that grade of steel in that country Needless to say that the availability of a particular grade of steel varies from country to country. Softwares are available, to optimize the amount of "High Yield Strength" and amount of "Low Yield Strength" steel to be used in a tower to get the maximum cost advantage, leveraging the cost differential of two grades of steel.
        However, such an exercise becomes useful only when large number of towers are required. A small saving in each tower can result in substantial reduction in total cost of all towers. Conclusion : Standard or Country of origin of steel chosen, has no effect on performance/ strength of tower, as long as the "Yield Strength " of steel used in design is equal to "Yield Strength " of steel actually used for manufacture. International / "or equivalent " standards , whenever specified are likely to result in more competition and better prices for buyer. Please scroll down to next page for tables.
        More attentions should be paid for chemical composition and physical property of steel. International / "or equivalent" standards, whenever specified are likely to result in more competition and better prices for buyer. More attentions should be paid for chemical composition and physical property of steel.

      • Question35. Is the height of my tower adequate?

        "Required Minimum Tower Height" in a communication system is determined by Radio path survey between 2 points. It is possible that shifting the location of tower by a small distance (i.e.100 to 200 meters)'Required Minimum Tower Height' is reduced to as much as half of the earlier value. Also, the LOS path is not a perfect straight line on available maps. Hence it is worthwhile and fruitful to invest time and money to determine the 'Required Minimum Tower Height' for a location. As to power transmission line tower, the minimum tower height determined by nominal height of tower, voltage grade of project, span distance, horizontal distance and sag calculation etc. MEGATRO equipped with experienced engineer with more than decade design, we can optimized tower height to get maximum cost saving.

      • Question 36. How much tightening should be done on the joint bolts?

        Whenever high tensile bolts are used in tower joints, it becomes necessary to tighten the bolts to predetermined tightness, because then and then only required strength of joint is achieved. However when joints are designed on the basis of shear strength only of bolts as happens in case of low strength bolts, the amount of tightening or friction does not contribute to the strength of joint. Therefore predetermined amount of tension in each bolt is NOT necessary. Only taking up of slack in the joint is required. MEGATRO follows the policy of using low Tensile Bolts, thus making the maintenance of tower much simpler and cheaper.

      • Question37. What is earthing and why is it necessary?

        Earthing or Grounding an object/tower means providing an electrical connection between that object/tower and mother earth, This electric connection is achieved by running an electrical wire/strip between the tower and an earth electrode. Earth electrode is a metal plate/pipe/sphere properly embedded at a depth in the earth. This Earthing/Grounding of tower is necessary to:
        a) Prevent damages to delicate instruments or humans due to stray voltages/currents
        b) For optimum performance of the communication system.

      • Question38. What is lightening arrestor and why is it necessary?

        Lightening arrestor is a conductive metal device mounted at the highest point on the tower. Tall objects like microwave tower are prone to damage by lightening strikes. The lightening strike occures due to induction effect between a charged cloud and the tower. To prevent the tower from lightening strike, a lightening arrestor is fitted on top of tower. This lightening arrestor or air electrode is connected to earth electrode through a conducting wire or strip. For details see Lightening

      • Question39. Should tower be painted before erection?

        It is a standard practice to paint the towers after erection. Electrical conductivity between members is an important requirement for performance of communication system as well as for lightening protection. Other reasons for painting the tower after erection are:
        1. Nut bolts cannot be painted before hand. After assembly, these nut bolts will stand out unpainted. Per haps repainting will be called for by the buyer.
        2. During erection of tower, it is necessary that electrical contact be maintained between members. If electrical contact is not maintained between the tower members, then there could be problems in the system performance. To get the electrical contact, it may become necessary to scrap the ends of members to get the contact. This scrapping cannot be precise, therefore repainting will be required.
        3. The ID markings on tower members is done in 2 ways simultaneously. a. Punch marks which are permanent and are about 0.6 mm deep. Galvanizing fills up the ID markings to certain extent but not fully therefore marks remain readable. b. Marking with permanent ink after galvanizing and before painting . The marks will get covered up by paint, if painting is done at factory. If marking with permanent ink is done after painting, then these marks will not look good aesthetically after erection of tower.
        Moreover the punch mark will also lose visibility to large extent because of leveling effect of paint. Hence factory painting of tower before erection is not recommended.
        4. The paint on members, gets damaged during transmit, because no elaborate packing is done on these steel members. Repainting, invariably is required after erection.

      • Question40.How about your tower take broken testing?

        In our china, generally we dispatch tower to CHINA ELECTRIC POWER RESEARCH INSTITUTE to take broken testing, which is located in Beijing and governed by Chinese government. The testing stations serve the objective of satisfying customers about design parameters of tower by subjecting Proto-Towers to various test load conditions. They are capable of testing all types of towers – Lattice Towers, Guyed Towers, Tubular and Mono Poles. The testing station can provide complete testing solutions to any type of transmission line requirements.

      86-532-55588298

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