管臺焊接程序課件

1、ASIA Construction Engineering Training Conference FY 2007ASIA CONSTRUCTION: BUILDING AIR PRODUCTS FUTURESeptember 18 to 22, 2006Weldolet welding techniqueWeldolet 焊接管臺Welding set up 管臺焊接的準(zhǔn)備Weldolet welding sequence 管臺焊接次序Especially note 注意事項(xiàng)Site photos 施工照片ASIA CONSTRUCTION: BUILDING AIR PRODUCTS FU

2、TUREWeldoletWelding set upLay out: the template is inside of the fittingCut hole: the hole in the run pipe on reducing sizes can be cut out either before or after the fitting is welded on. The hole can be cut with drill or a hole saw. Welding the fitting to run pip prior to cutting the hole helps pr

3、event distortion of the run pipe and can be done generally on outlet size over two inches 放置模板于管臺內(nèi)部 開孔：變徑管臺在主觀上的開孔既可以在焊接前也可在焊接后再開?？梢杂勉@孔，也可用孔據(jù)開孔。先在主管上焊管臺后開孔可以防止主管扭曲， 一般適用大于2英寸的管臺。Welding set upSpace for welding: The weldolet is raised off the run pipe to establish proper weld gap by placing spacers,

4、e.g. welding rods under the fitting. This provides a uniform welding gap between the curvature of the run and base of fitting 焊接間隙：管臺焊接前要保證與主管的焊接間隙， 例如放一根焊條在管臺和主管之間。這樣可以保證焊接根部間隙均勻。Welding sequenceLongitudinal section: Wide bases or footings at crotch section distribute internal and external stresses

5、. Gradual changes of section eliminate stress concentration. Funnel shaped opening provides improved flow direction 縱斷面：分叉處存在內(nèi)外應(yīng)力， 截面漸變消除了應(yīng)力集中。漏斗狀開口有利于流體流動(dòng)。Welding sequenceTransverse section: Note the blending of the skirt section weldolet to the run pipe to avoid abrupt change in intersection. Thro

6、at of weld at this point is designated by the welding bevel. 橫斷面：管臺裙叉處和主管處的坡口過渡可以避免交叉點(diǎn)的急劇變化， Welding sequenceStringer bead: The stringer bead is applied completely around the base of the fitting. The established weld gap assures full penetration線型焊道：線型焊道緊緊環(huán)繞管臺焊接，焊道間隙可以保證完全焊透。 Welding sequenceReinfor

7、cing beads: Reinforcing welds should be made at the crotch bevel areas of the fitting to provide maximum weld at the crotch tapering to minimum at the skirt. Particular are should be taken to weld only the bevel portion of the fitting. This eliminates the unnecessary use of continuous passes and pre

8、vents the erroneous practice of welding up to the rib on the skirt portion of fitting. A continuous cover bead should be added to fill the bevel and provide a smooth tapered weld. 加強(qiáng)焊道：加強(qiáng)焊道應(yīng)該在管臺分叉處坡口進(jìn)行最大焊接， 而在裙尖處進(jìn)行最小焊接，特別是焊接坡口部分。這就是說可以減少一些連續(xù)焊接， 防止裙尖處的過渡焊接。連續(xù)的焊接應(yīng)填滿坡口，然后漸縮到裙尖處。Welding sequenceEspecial

9、ly noteWhen using the charts in MSS SP-97 when the pipe wall schedule actually being used is heavier than listed in the chart you need to use the next higher chart dimensions. This is based on on Table 1 and note (a) where since our run pipe schedule is Sch 80 (wall thickness=0.938) and not XS (wall

10、 thickness=0.500) you need to use the SCH 160 class fittings and dimensions which means we need to usethe105mm dimension. Purchase and Inspection materials should know this principle . 當(dāng)用MSS SP-97 查支管道壁厚時(shí)，表中壁厚應(yīng)該采用高一級的尺寸。例如：當(dāng)我們知道主管壁厚是Sch 80， 我們應(yīng)該采用 SCH 160 class 的管臺尺寸，見表。 所以采購和檢查時(shí)應(yīng)知道這個(gè)道理。Especially n

11、oteWeldolet welding often occurred issue : non- penetrationFor 4 and above, it could be welded at both side, even there is some difficulty with back gouging and back welding But for 3 and blower, it is not accessible with back gouging and back welding, the reason is 1) The torch size welding at back

12、 side is impossible access, and sometimes the torch could not access the bevel well at some angle. 2) The ID of weldolet and opening in run pipe has some deviation. 3) The bevel curve of weldolet do not fit pipe well.Once found non penetration, need to cutting off the weldolet, reweld it from the ru

13、n pipe to achieve penetration as could as possible. 12 mm non-penetration is acceptable. If more than 2mm non-penetration, back side need be welded. 管臺焊接常出現(xiàn)未焊透問題： 大于等于4寸的管臺，可以從內(nèi)外兩邊焊，雖然有時(shí) 內(nèi)部清根焊接有點(diǎn)困難 3寸及3寸以下管臺， 內(nèi)部無法清根和焊接的原因如下 1）焊把尺寸大不易接近內(nèi)部， 有時(shí)角度不好而未焊透 2）管臺內(nèi)經(jīng)合開孔又偏差 3）管臺坡口曲線 與管道不匹配3寸及3寸以下管臺一旦發(fā)現(xiàn)未焊透， 需要割掉管臺重新焊接或從主管道內(nèi)部焊接。12 m