低溫焊接與銀釬焊

務必記住所推薦的閥門的用途是什么，并對所應用的環境進行分析，這樣才能決定最適合于安裝什么樣的閥門。在安裝正確的閥門之前，為了防止損壞閥門，移動泵車并保證充分發揮閥門的工作性能，請閱讀一下安裝指南。

1.先沿著垂直方向切割管道，并修整、去除毛刺，測量管徑。

2.使用紗布或鋼絲刷清除管道和切割部位，使其金屬表面發光發亮。建議不要使用鋼絲絨。

3.在管道的外面和焊接罩的內部涂上焊劑，焊劑必須完全覆蓋焊接表面。請有節制地使用焊劑。

4.要確保閥門處于開啟狀態。先對管道加熱。盡可能多的將熱從管道傳遞到閥門。避免延長閥門本身的加熱時間。

4a. 銀釬焊的方法：

　　對需要進行釬焊的部件進行組裝。如果允許涂上焊劑的部件處于直立狀態，那么焊劑中的水分會蒸發掉，而干燥的焊劑很容易脫落，致使暴露的金屬表面容易被氧化。在進行連接組裝時，要將管道插入管套直到遇到阻擋為止。組裝是要保證有穩固的支撐，使得整個釬焊操作過程中能夠保持在直線位置。

注：對于1英寸或更大公稱通徑的閥門，一次性將連接部件加熱到所需溫度比較困難。為了在整個大面積上保持正常的溫度，通常情況下需要兩個焊槍。建議對整個管套區域進行適當的預熱。建議采用乙炔火焰對連接部件進行加熱。首先從離閥門1英寸的地方開始對管道進行加熱，然后圍繞著管道短距離上下交替對管道進行火焰烘烤，并以適當的角度旋轉管道，避免燒穿管道?；鹧嬉B續運動，不允許停留在某一點上。

在閥門的套筒底座用火焰進行烘烤。加熱要均勻，用火焰對閥門及管道進行火焰烘烤的過程要延續到閥門上的焊劑不再發出聲音。不要對閥門過度加熱。

當焊劑變成液態并且在管道和閥門上呈現半透明狀態時，開始將火焰沿著連接部件的軸線進行進退烘烤，以保持連接部件、特別是閥門套筒底座部位的熱度。

5.使用適量的焊料：自吸泵車如果使用線狀焊料，那么對公稱通徑為3/4英寸的閥門就要采用3/4英寸的焊料，等等。如果使用的焊料太多，那么有些焊料可能會流過管道阻擋部位，并堵塞密封區域。在安裝連接部件時，可以看到焊料和釬焊合金繼續流動

5a. 銀釬焊法：

　　將焊線或焊桿點在閥門里的管道套座上。當焊桿或焊線進入連接處時要將火焰從其上面移開。當合金流進連接處時，要前后移動火焰。達到適當的溫度后，合金將迅速容易地流進管道外殼和閥門套管之間的空間。連接處被充滿后，就會看到焊接合金的邊緣。

6.當焊料處于粘滯狀態時，用刷子把多余的焊料清除干凈。焊料冷卻后，將一條嵌條環繞在閥門的端口。

銀釬焊

　　如果采用不同的釬焊材料，其釬焊連接的強度并不見得很好，強度大小取決于管道外殼與閥門套管之間正常的、大范圍的清潔維護工作。銀釬焊的閥門套管的內部直徑的機械公差和表面光滑度要求非常精確，以確保有足夠的附著力。

　　 注意：在清理和清除過程中，應該細心的觀察清洗介質的殘留物。在已經弄臟或不正確清洗的表面上進行釬焊，焊接效果就很難令人滿意，因為銀釬焊合金并不會流過或粘接在氧化物上，而油污的表面及暴露的、容易氧化和導致空隙和雜物排斥焊劑。

螺紋連接

　　硬渣、污物或任何外部物質在管道內積累都可能妨礙閥門的工作效率并嚴重損壞閥門的關鍵部件。必須用空氣或蒸氣對管道內部進行徹底清洗。

　　 當對管道進行攻絲時，要測定管道螺紋的尺寸和長度，避免將管道塞滿閥座和閥瓣。徹底清洗螺紋末端，清除任何有害的鋼或鐵沉淀物。如果要時焊接更牢固，就要使用特氟隆帶或管道粘接劑。在管道螺紋上只能少量使用管道粘接劑，但是在閥門螺紋上絕對不能使用管道粘接劑。不要讓任何管道粘接劑流入閥體內，以避免損壞閥瓣和閥座。

　安裝前，切斷通過閥門的流體，以使閥門工作正常。安裝前要完全關閉閥門。將扳手套在靠近管道的六角螺栓頭上避免可能產生的變形。加藥裝置安裝閥門后，要支撐住管道：下垂的管道會使閥門產生變形而導致失敗。

法蘭連接

　　為了確保正確進行閥蘭連接安裝，需要遵循如下幾個步驟。首先細心地清洗連接處，然后，在底座部松散地裝上兩個或三個螺栓。接著，小心的將墊片插入連接處。底部螺栓有助于對墊片進行定位，并保持恰當的位置。然后插入螺栓要采用交叉旋緊的方式，不要采用環繞旋緊的方式，這樣有助于消除過于集中的壓力）。在正常使用一段時間后，要檢查核對所有的螺栓是否旋緊，并進行必要的再旋緊。

SOLDERING AND SILVER BRAZING

Analyze the application to determine which valve is best suited for installation, keeping in mind the service for which the valve is recommended. Before installing the correct valve, review the installation instructions to prevent damage to the valve and assure its maximum efficiency.

1.Cut tube end square. Ream, burr and size.

2.Use sand cloth or steel wire brush to clean both tube and cut to bright metal. Steel wool is not recommended.

3.Apply flux to outside of tube and inside of solder cup. Surfaces to be joined must be completely covered. Use flux sparingly.

4.Be sure that valve is fully open. Apply heat to tube first. Transfer as much heat as possible through tube into valve. Avoid prolonged heating of valve itself.

4a. Silver Brazing Method:

　　 Assemble parts to be brazed. If fluxed parts are allowed to stand, the water in the flux will evaporate; and dried flux is liable to flake off, exposing metal surfaces to oxidation. Assemble joint by inserting tube into socket hard against the stop. The assembly should be firmly supported so that it will remain in alignment during the brazing operation.

NOTE: On one inch and large valves, it is difficult to bring the whole joint up to temperature at one time. It will frequently be found desirable to use a double tip torch to maintain the proper temperature over the large area. A mild pre-heating of the whole socket area is recommended. Apply heat to parts to be joined. The preferred method is by oxy-acetylene flame. Heat tube first, beginning one inch from edge of valve. Sweep flame around tube in short strokes up and down at right angles to run of tube. To avoid burning through tube, the flame should be in continuous motion and not allowed to remain on any one point.

Apply flame to valve at base of socket. Heat uniformly, sweeping flame from valve to tube until flux on valve becomes quiet. Avoid excessive heating of valve.

When flux appears liquid and transparent on both tube and valve, start sweeping flame back and forth along axis of joint to maintain heat on parts to be joined, especially toward base of valve socket.

5.Use just enougn solder: with wire solder, use 3/4" for a 3/4" valve, etc. If too much solder is used, it may flow past tube stop and clog sealing area. When joint is filled, a continuous run of solder or brazing alloy will be visible.

5a. Silver Brazing Method:

　　 Apply brazing wire or rod at point where tube enters valve socket. Keep flame away from rod or wire as it is fed into the joint. Move flame back and forth as alloy is drawn into joint. When the proper temperature is reached, alloy will flow readily into space between tube outer wall and valve socket. When joint is filled, a continuous rim of brazing alloy will be visible.

6.Remove excess solder with small brush while plastic, leaving a fillet around end of valve as cools.

SILVER BRAZING

The strength of a brazed joint does not vary appreciably with the different brazing materials, but depends to a large extent upon the maintenance of proper clearance between the outside of the tube and the valve socket. The interior dimensions of silver brazing valve sockets are machined to the closest tolerances and finished smooth to promote full capillary attraction.

NOTE: Care should be observed in cleaning and in removing residues of the cleaning medium. Attempting to braze a contaminated or improperly cleaned surface will result in an unsatisfactory joint. Silver brazing alloys will not flow over or bond to oxides. Oily or greasy surfaces repel fluxes, leaving bare spots which oxidize and result in voids and inclusions.

THREADING

Grid, dirt or any foreign matter accumulated in the pipe can hinder efficient valve operation and seriously damage vital valve parts. Thoroughly clean pipe internally with air or steam.

When threading pipe, gauge pipe threads for size and length to avoid jamming pipe against seat and disc. Thoroughly clean threaded end to remove any harmful steel or iron deposits. For a good joint, use teflon tape or pipe dope. If pipe dope is used, apply sparingly on pipe threads, never on valve threads. Do not allow any pipe dope into valve body in order to avoid damage to disc and seat.

Before installation, check line of flow through valve so that valve will function properly. Close valve completely before installation. Apply wrench to hex next to pipe and guard against possible distortion. After installation of valve, support line; a sagging pipe line can distort the valve and cause failure.

FLANGED

There are several steps to follow to make sure that a flanged joint will be properly assembled. First clean the joint carefully. Then loosely assemble the joint by putting in the bottom two or three bolts. Then carefully insert the gasket into place. The bottom bolts will help locate gasket and hold it in position. Then insert the rest of the bolts into place and tighten all of the bolts evenly - not in rotation, but by the cross over method to load the bolts evenly and eliminate concentrated stresses. The bolts should be checked for tightness after an appropriate interval of use and retightened if necessary.