低溫焊接與銀釬焊

務(wù)必記住所推薦的閥門(mén)的用途是什么，并對(duì)所應(yīng)用的環(huán)境進(jìn)行分析，這樣才能決定*適合于安裝什么樣的閥門(mén)。在安裝正確的閥門(mén)之前，為了防止損壞閥門(mén)，并保證充分發(fā)揮閥門(mén)的工作性能，請(qǐng)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(cè)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(fā)光發(fā)亮。建議不要使用鋼絲絨。
3.在管道的外面和焊接罩的內(nèi)部涂上焊劑，焊劑必須完全覆蓋焊接表面。請(qǐng)有節(jié)制地使用焊劑。
4.要確保閥門(mén)處于開(kāi)啟狀態(tài)。先對(duì)管道加熱。盡可能多的將熱從管道傳遞到閥門(mén)。避免延長(zhǎng)閥門(mén)本身的加熱時(shí)間。
4a. 銀釬焊的方法：
　　對(duì)需要進(jìn)行釬焊的部件進(jìn)行組裝。如果允許涂上焊劑的部件處于直立狀態(tài)，那么焊劑中的水分會(huì)蒸發(fā)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(jìn)行連接組裝時(shí)，要將管道插入管套直到遇到阻擋為止。組裝是要保證有穩(wěn)固的支撐，使得整個(gè)釬焊操作過(guò)程中能夠保持在直線(xiàn)位置。
注：對(duì)于1英寸或更大公稱(chēng)通徑的閥門(mén)，一次性將連接部件加熱到所需溫度比較困難。為了在整個(gè)大面積上保持正常的溫度，通常情況下需要兩個(gè)焊槍。建議對(duì)整個(gè)管套區(qū)域進(jìn)行適當(dāng)?shù)念A(yù)熱。建議采用乙炔火焰對(duì)連接部件進(jìn)行加熱。首先從離閥門(mén)1英寸的地方開(kāi)始對(duì)管道進(jìn)行加熱，然后圍繞著管道短距離上下交替對(duì)管道進(jìn)行火焰烘烤，并以適當(dāng)?shù)慕嵌刃�轉(zhuǎn)管道，避免燒穿管道�；鹧嬉�連續(xù)運(yùn)動(dòng)，不允許停留在某一點(diǎn)上。
在閥門(mén)的套筒底座用火焰進(jìn)行烘烤。加熱要均勻，用火焰對(duì)閥門(mén)及管道進(jìn)行火焰烘烤的過(guò)程要延續(xù)到閥門(mén)上的焊劑不再發(fā)出聲音。不要對(duì)閥門(mén)過(guò)度加熱。
當(dāng)焊劑變成液態(tài)并且在管道和閥門(mén)上呈現(xiàn)半透明狀態(tài)時(shí)，開(kāi)始將火焰沿著連接部件的軸線(xiàn)進(jìn)行進(jìn)退烘烤，以保持連接部件、特別是閥門(mén)套筒底座部位的熱度。
5.使用適量的焊料：如果使用線(xiàn)狀焊料，那么對(duì)公稱(chēng)通徑為3/4英寸的閥門(mén)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(huì)流過(guò)管道阻擋部位，并堵塞密封區(qū)域。在安裝連接部件時(shí)，可以看到焊料和釬焊合金繼續(xù)流動(dòng)
5a. 銀釬焊法：
　　將焊線(xiàn)或焊桿點(diǎn)在閥門(mén)里的管道套座上。當(dāng)焊桿或焊線(xiàn)進(jìn)入連接處時(shí)要將火焰從其上面移開(kāi)。當(dāng)合金流進(jìn)連接處時(shí)，要前后移動(dòng)火焰。達(dá)到適當(dāng)?shù)臏囟群�，合金將迅速容易地流進(jìn)管道外殼和閥門(mén)套管之間的空間。連接處被充滿(mǎn)后，就會(huì)看到焊接合金的邊緣。
6.當(dāng)焊料處于粘滯狀態(tài)時(shí)，用刷子把多余的焊料清除干凈。焊料冷卻后，將一條嵌條環(huán)繞在閥門(mén)的端口。

銀釬焊

　　如果采用不同的釬焊材料，其釬焊連接的強(qiáng)度并不見(jiàn)得很好，強(qiáng)度大小取決于管道外殼與閥門(mén)套管之間正常的、大范圍的清潔維護(hù)工作。銀釬焊的閥門(mén)套管的內(nèi)部直徑的機(jī)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(guò)程中，應(yīng)該細(xì)心的觀察清洗介質(zhì)的殘留物。在已經(jīng)弄臟或不正確清洗的表面上進(jìn)行釬焊，焊接效果就很難令人滿(mǎn)意，因?yàn)殂y釬焊合金并不會(huì)流過(guò)或粘接在氧化物上，而油污的表面及暴露的、容易氧化和導(dǎo)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(zhì)在管道內(nèi)積累都可能妨礙閥門(mén)的工作效率并嚴(yán)重?fù)p壞閥門(mén)的關(guān)鍵部件。必須用空氣或蒸氣對(duì)管道內(nèi)部進(jìn)行徹底清洗。
　　 當(dāng)對(duì)管道進(jìn)行攻絲時(shí)，要測(cè)定管道螺紋的尺寸和長(zhǎng)度，避免將管道塞滿(mǎn)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(shí)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(mén)螺紋上絕對(duì)不能使用管道粘接劑。不要讓任何管道粘接劑流入閥體內(nèi)，以避免損壞閥瓣和閥座。
　安裝前，切斷通過(guò)閥門(mén)的流體，以使閥門(mén)工作正常。安裝前要完全關(guān)閉閥門(mén)。將扳手套在靠近管道的六角螺栓頭上避免可能產(chǎn)生的變形。安裝閥門(mén)后，要支撐住管道：下垂的管道會(huì)使閥門(mén)產(chǎn)生變形而導(dǎo)致失敗。

法蘭連接

　　為了確保正確進(jìn)行閥蘭連接安裝，需要遵循如下幾個(gè)步驟。首先細(xì)心地清洗連接處，然后，在底座部松散地裝上兩個(gè)或三個(gè)螺栓。接著，小心的將墊片插入連接處。底部螺栓有助于對(duì)墊片進(jìn)行定位，并保持恰當(dāng)?shù)奈恢�。然后插入螺栓要采用交叉旋緊的方式，不要采用環(huán)繞旋緊的方式，這樣有助于消除過(guò)于集中的壓力）。在正常使用一段時(shí)間后，要檢查核對(duì)所有的螺栓是否旋緊，并進(jìn)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.