JB/T 7949-1999 JB/T 7949-1999 Steel structure weld dimensions JB/T7949-1999 Standard download decompression password: www.bzxz.net

JB/T7949-1999
This standard is a revision of JB/T7949-95 "Outer dimensions of welds for steel structures". During the revision, editorial changes were made to the original standard, and its main technical content remained unchanged. This standard replaces JB/T7949-95 from the date of implementation. This standard is proposed and managed by the National Technical Committee for Welding Standardization. The responsible drafting units of this standard are Harbin Welding Research Institute and Dalian Crane Factory. The main drafters of this standard are Ji Wenjing and Sun Yuying. This standard was issued as GB10854 in 1989 and adjusted to JB/T7949 in 1995. This revision is the first revision. 275
1 Scope
Machinery Industry Standard of the People's Republic of China
Outer dimensions of welds for steel construction
Weld outer dimensions for steel construction This standard specifies the outer dimensions of welds for welded joints in steel structures. This standard applies to the inspection of the external dimensions of fusion welded butt and fillet joints of steel structures. 2 Referenced standards
JB/T 7949--1999
Replaces JB/T7949--95
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T324--1988 Welding symbol representation
GB/T985-1988 Basic forms and dimensions of weld grooves for gas welding, manual arc welding and gas shielded welding GB/T986-1988 Basic forms and dimensions of weld grooves for submerged arc welding 3 General
3.1 Before inspecting the external dimensions of welds, the weld and both sides must be cleaned of slag, spatter and other contaminants. 3.2 The weld dimension inspection is mainly carried out with the naked eye with the help of relevant auxiliary measuring tools. Good lighting should be ensured during the inspection. 3.3 The groove form and size of the weld should comply with the relevant provisions of GB/T985 and GB/T986: 3.4 The marking of the weld dimension should be carried out in accordance with the relevant provisions of GB/T324. 4 Dimensions
4.1 The weld shape should be evenly hooked, and the transition between welds and welds and between welds and base metals should be smooth. 4.21-shaped groove butt weld (including 1-shaped butt weld with pad) See Figure 1. Its weld width cb+2a and the value of the excess height shall comply with the provisions of Table 1.
Figure 11-shaped groove butt weld dimensions
4.3 Non-I-shaped groove butt weld (welds of various butt groove forms except I-shaped groove in GB/T985 and GB/T986) See Figure 2. The weld width c=g+2u and the value of the excess height shall comply with the provisions of Table 1. Approved by the State Bureau of Machinery Industry on June 24, 1999 276
Implementation on January 1, 2000
Welding methods
Manual arc welding
and gas shielded welding
JB/T 7949--1999
Figure 2 Dimensions of non-I-shaped groove butt welds
Welding seam form
I-shaped weld
Non-shaped weld
I-shaped weld
Non-shaped burst line
Weld seam width
The values ​​in Table 5 are the actual assembly values ​​that meet the requirements of GB/T985 and GB/T986. 2g value calculation result, if it contains decimals, can be calculated to integer by digital rounding method, g value is calculated according to formula (1) and formula (2), and see Figure 3. a)
Figure 3a):
Figure 3b):wwW.bzxz.Net
Figure 3 Schematic diagram of book value calculation
g-6+2(8-P)tanβ....
Welding seam excess height h
Flat welding: 0~3
Others: 0~4
g=2R+h+2(aR--P)tan...
4.4 The difference between the maximum weld width cmx and the minimum weld width cmin shall not be greater than 4mm within any 50mm weld length range, and shall not be greater than 5mm within the entire weld length range.
4.5 Weld edge straightness f, within any 300mm continuous weld length, the weld edge straightness f along the weld axis is shown in Figure 4, and its value shall comply with the provisions of Table 2.
JB/T 7949-1999
Figure 4 Schematic diagram of weld edge straightness
Table 2 Weld edge straightness
Welding method
Buried coal
Manual arc welding and gas shielded welding
Weld edge straightness!
4.6 Weld surface convexity, within any 25mm length of the weld, the difference of weld excess height hmx-hmn shall not be greater than 2mm, see Figure 5. Schematic diagram of weld surface convexity
The weld leg size K value of the fillet weld shall be indicated by the design or relevant technical documents, and the deviation of its weld leg size K value shall comply with the provisions of Table 3. 4.7
Table 3 Permissible deviation of weld leg dimensions
Welding method
Submerged arc welding
Manual arc welding and gas shielded welding
K≥12
When the weld dimensions exceed the above requirements after inspection, they should be ground or partially repaired according to a certain process. After repair, they should meet the requirements of this standard. And the repaired weld should maintain a smooth transition with the original weld. 6 Special weld dimensions can be implemented with reference to relevant standards and technical conditions. 278
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