Scope of application

It is mainly applicable to the installation construction method and quality standard of ordinary bolts, torsional shear type high-strength bolts, large hexagon head high-strength bolts, rivets, self tapping screws, pull rivets, shooting nails, anchor bolts, anchor bolts and other fastener standard parts in steel structure installation;

The fastener installation construction of steel structure frame in other fields and uses can also be referred to.

Construction requirements

The main construction equipment and machines and tools shall be prepared before the installation and construction; the prefabrication and assembly inspection of all parts and components shall be completed; the construction site and discharge material site shall be prepared before the installation, and the construction conditions shall be met;

All the personnel who refer to the construction have participated in the construction technical disclosure, and have defined the construction procedures, construction methods, installation procedures, quality standards, finished product protection and HSE technical requirements;

The construction team leader and post leader shall be familiar with the construction drawings, standard atlas, construction and acceptance standards and specifications;

The variety, specification and performance of the delivered products shall comply with the current national product standards and design requirements, with product quality documents.The inspection report of torque coefficient and tightening axial force (pre tension) shall be attached to the box for high strength large hexagon head bolt connection pair and torsion shear type high strength bolt connection pair when they leave the factory;

a) High strength bolt connection pairs shall be supplied in accordance with the packing box, and the batch number, specification, quantity and production date shall be indicated on the packing box.The appearance surface of bolts, nuts and washers shall be protected with oil, without rust and dirt, and the thread shall not be damaged;

b) When ordinary bolts are used as permanent connecting bolts, when there are design requirements or doubts about their quality, the minimum tensile load of bolts shall be rechecked, and 8 bolts of each specification shall be sampled;

c) The torque coefficient of high strength large hexagon head bolt connection pairs should be retested and an inspection report should be issued. Eight sets of connection pairs were selected from each batch for re inspection. After the re inspection, the average value of torque coefficient of 8 sets of connection pairs in each group should be 0.110 ~ 0.150, and the standard deviation should be less than or equal to 0.010;

d) The pre tension re inspection shall be conducted for the connection pairs of torsional shear high strength bolts and the inspection report shall be issued. Eight sets of connection pairs shall be selected from each batch for re inspection. The average value and standard deviation of pre tension shall meet the requirements in the following table:

e) For the steel grid structure with bolt ball joint whose safety level is grade I and span is 40m and above, surface hardness test shall be conducted for high-strength bolts, and 8 bolts shall be selected according to the specification.The hardness of grade 8.8 high-strength bolt should be hrc21-29; the hardness of grade 10.9 high-strength bolt should be hrc32-36, and there should be no crack or damage.

f) During transportation and storage, the high strength bolt connection pair must be loaded and unloaded lightly, and the thread shall not be damaged;

g) High strength bolt connection pairs shall be classified and kept according to the batch number and specification on the packing box. It is forbidden to open the box arbitrarily before use to prevent contamination with stolen goods;

h) The high-strength bolts shall be collected according to the required quantity on the same day. The warehouse shall register the receiver, specification, quantity and position of use. The remaining bolts shall be properly kept and shall not be thrown or placed. 

Construction process

Construction method

Inspection and acceptance of connectors before construction

The connecting parts delivered shall meet the relevant requirements of “steel parts and steel parts processing engineering” and “steel component assembly engineering” in the code for construction and acceptance of steel structure engineering.In addition, for the steel structure with high strength bolt connection, the following requirements are required for its members:

The steel plate surface of the component at the high-strength bolt connection shall be flat without welding spatter, burr and oil stain. The surface treatment method shall be consistent with the requirements of the drawing, and the friction surface shall not be painted;

The bolt hole diameter and hole distance of the component meet the requirements of the drawing after inspection;

The friction surface of high-strength bolt connection of components shall be protected after treatment to prevent contamination with dirt and oil;

The delivered components shall be provided with product quality certificate and test report on anti sliding coefficient of friction surface;

★ Before the installation of steel structure, the anti sliding coefficient of friction surface of high-strength bolts shall be rechecked with the manufacturing batch of steel structure as the unit. The manufacturing batch can be divided into several parts (sub distribution) projects. Every 2000t is regarded as a batch, and those less than 2000t can be regarded as a batch. Each batch of three groups of test pieces shall be provided by the manufacturer. The re inspection report shall be provided after the test. The minimum value of inspection must be equal to or greater than the designIf the specified value is not met, the friction surface of the component must be treated again, and the inspection shall be conducted again after the treatment.

The surface treatment of the connected components shall be carried out. Before installation, the high-strength bolt connection surface of the components shall be checked, and the flash, burr, welding spatter, welding scar, oxide skin, dirt and rust on the friction surface shall be removed with steel wire brush, sandpaper, grinding machine and other tools.

The installation method and quality standard requirements of structural members are shown in the steel structure installation construction method

Installation of fasteners

The installation of permanent ordinary bolts shall be firm and reliable, and the penetration direction shall be consistent. The exposed screw threads shall not be less than 2. If the ordinary bolts are only used for fixation, other requirements in the design drawings such as welding of components shall be paid attention to.

Installation of self tapping bolts, rivets and rivets

a) The specifications and sizes of self tapping bolts, rivets and rivets used for connecting thin steel plates shall match with the steel plates to be connected, and the spacing and edge distance shall meet the design requirements;

b) The self tapping bolts, rivets and rivets shall be connected, and the steel plates shall be tightly attached and orderly arranged in appearance.

High strength bolt installation

a) The length and quantity of high-strength bolts shall meet the requirements of design drawings; if the design drawings (including secondary design drawings) do not specify the length and quantity summary of high-strength bolts at nodes, the length can be calculated according to the following formula and in combination with node drawing, part drawing and component drawing of design drawing:

The number of high-strength bolts can be summarized according to the node type and node number.

b) The contact surface clearance caused by plate thickness tolerance, manufacturing deviation, installation deviation, etc. shall be treated as follows: 

1）When the contact surface clearance t is less than 1 mm, no treatment is needed.As shown in Figure 07-1 

When the contact surface clearance t is between 1 mm and 3 mm, one side of the thick plate is ground into a gentle slope of 1:10.As shown in Figure 03-2

When the friction surface clearance t is greater than 3 mm, the thickness of the base plate shall not be less than 3 mm, and the number shall not be more than 3 layers; the material of the base plate and the treatment method of the friction surface are the same as those of the components.As shown in figure 03-3

c) High strength bolts should be freely penetrated into the bolt holes. If they can not be penetrated freely, reaming should be carried out with a reamer or a bar grinder. The hole diameter after reaming should not exceed 1.2D (D is the bolt diameter). It is strictly forbidden to use gas cutting tools for reaming. Before reaming, all the bolts around should be tightened to prevent iron chips from falling into the plate gap;

d) If most of the high-strength bolts of the whole node can not be penetrated freely due to manufacturing, installation and other reasons, the bolt holes of the components shall be blocked with welding method, expanded drilling or re drilling after grinding according to the design agreement. Welding rod with mechanical properties equivalent to the base metal shall be used during welding, and steel block, steel bar and round steel bar shall not be used for filling; 

e) In order to accurately and quickly install the high-strength bolts of nodes, temporary baffles can be welded on the components; at the same time, round pins or temporary bolts should be used to align the bolt holes of connecting plates and connectors. The number of temporary bolts should meet the strength requirements, and then the formal bolts should be installed in time. After installing about 1 / 3 of the formal bolts, the round pins or temporary bolts can be removed, and the high-strength bolts can be removed after tighteningTemporary baffle, and polish and repair the welding scar at the baffle welding position;

f) The installation of bolts shall be carried out after the adjustment of the central position of structural members. The penetration of bolts shall be subject to the convenience of construction and shall be unified as far as possible. The installation direction of bolts at both ends of the same component shall be the same, the installation direction of bolts at component nodes on the same axis shall be consistent, and that of structural members of the same frame and device shall be consistentThe installation direction of bolts should be consistent, and some nodes may not be constructed in accordance with the above requirements due to inconvenient installation. Generally speaking, for the sake of beauty, the bolt head should be on the outside of the components of the outer structure;

g) When installing the high strength bolt connection pair, the side of the nut with the cone should face the side with chamfer of the washer; for the large hexagon head high strength bolt connection pair, the side with chamfer of the washer under the bolt head should face the bolt head;

h) The friction surface of the high-strength bolt connection must ensure that the treatment method has been determined and shall not be changed without authorization; and the friction surface shall be kept dry. If the construction is carried out in rainy days, rain proof measures must be taken;

i) In order to facilitate the installation, the high-strength bolts of the component can be fixed on both sides of the component with iron wire after being installed (the quantity should not be too much), and the repeatedly used tools such as tool bag should be checked regularly to see if they are in good condition;

j) After the installation of high-strength bolts, special spanners should be used for tightening in time. In order to speed up the construction progress, ring spanners and solid spanners can be used to tighten the nuts until they are close to the connecting plate. The torque wrench for construction should be corrected;

k) The construction torque of large hexagon head high strength bolt can be determined by the following formula:

l) The tightening of large hexagon head high strength bolts should be divided into initial tightening and final tightening; for large joints, it should be divided into initial tightening, re tightening and final tightening. The initial tightening torque is about 50% of the construction torque, and the re tightening torque is equal to the initial tightening torque. The high-strength bolts after initial tightening and re tightening should be marked on the nuts with color, and the high-strength bolts after final tightening should be marked on the nuts with another colorWhen tightening the hexagon head high strength bolt, only the torque is allowed to be applied on the nut;

m) The tightening of torsion shear type high strength bolt is divided into initial tightening and final tightening.For large joints, it should be divided into initial tightening, re tightening and final tightening, and the re tightening torque is equal to the initial tightening torque.The initial tightening torque is obtained from table 07-4

n) During the initial tightening, re tightening and final tightening of high strength bolts, the bolts at the joints shall be screwed in a certain order.For a certain node, the bolt group should be screwed from the center to the outside, so that the deformation of the plate can expand outward during the process of tightening; for the whole structure, it should be screwed from bottom to top and from one side to the other side;

o) The initial tightening, re tightening and final tightening of high strength bolts shall be completed on the same day;

p) For steel structures used in the open air, exposed to corrosive gases or required by the design drawings, after the high-strength bolts are tightened and accepted, the joints at the connecting plates shall be sealed with putty in time. The putty materials shall meet the design requirements, and the proportion of putty shall meet the requirements of the manufacturer’s product instructions. The joints of high-strength bolts shall be painted according to the design requirements. 

quality standard

Quality inspection and acceptance of large hexagon head high strength bolt connection pair:

1）Knock the high-strength bolt with 0.3KG hammer for general survey, and check whether there is missing screw; 

2）Check the tightening torque: check 10% of the number of bolts in each node, but no less than one.Take any bolt, draw a straight line on the screw end face and nut, loosen the nut by 60 ° and then re tighten it with a torque wrench to make the two lines coincide. At this time, the measured torque should be within the range of 0.9tch ~ 1.1tch.Check torque (TCH) is calculated as follows: TCH = k × P × D (n · m) 

3）If any non-compliance is found, the inspection shall be expanded by 10% on the joint; if there is still unqualified, the high-strength bolts of the whole joint shall be re tightened; 

4）The torque inspection should be completed after 1 hour and before 24 hours after the final tightening of bolts; 

The final tightening inspection of high-strength bolt of torsion shear type is qualified when the tail plum head is broken.For the torsion shear type high-strength bolts that cannot be tightened with special spanner, the inspection method of large hexagon head high-strength bolts shall be carried out;

The reaming quantity meets the requirements of relevant technical documents and specifications;