MKS Series 23 is a family of buttweld vacuum fittings

manufactured by MKS Instruments, Inc. They are designed

to be used in conjunction with the full line of ISO-Universal,

ISO-KF and CF UHV flanges, and are easily welded to

the flanges or each other during on-site installation. All

components are made of type 304 stainless steel and are

specifically prepared for use in high vacuum process or

UHV applications.

Applications

Vacuum buttweld fittings are designed to be used in any

vacuum applications where minimizing the number of

sealed joints is critical.

• Semiconductorwaferfabricationareasforremote

installations and below a raised floor

• Permanenthousevacuumlines

• Vacuumutilitylinesforvacuumfixtures

• Hightemperaturelines

• Burnboxexhaustlines

Component Construction

The Series 23 components are constructed of 304 or

304L welded, drawn, and annealed stainless steel tubing.

(316L is available on request.) For most vacuum process

applications, this provides the best combination of the

following critical features:

• Lowoutgassingundervacuum

• Chemicallyresistant

• Annealedforconsistentleakfreewelding

• Minimizedcorrosionconcentrationpoints

• Goodavailability

• Costconsistentwiththeaboverequirements

Each component is fabricated using pulled port and 100%

penetrationTIGweldtechniques.Allweldedcomponents

are leak free, carefully cleaned for high vacuum use and

then packaged to remain clean until the time of installation.

Installation

Series 23 fittings are designed to be welded using

techniques preferred for vacuum applications. These

techniques include internal (socket type) welding and

external buttwelding. The most commonly used type of

weldforhighvacuumapplicationsisaTIG(Tungsten

InertGas)fusionweld,preferablywithoutfillerrod.Forthe

best results, remove components from packaging in clean

conditions during installation. Handle the components with

clean gloves and equipment in the absence of any fibers,

fingerprint oils, or other greases. If these precautions

are taken, the weld is more likely to be leak free and the

integrity of the vacuum surface will remain intact and ready

for use.

Generalhintsforgoodvacuumweldsinclude:

1. Always start with clean and properly weld prepped

components.

2. For internal welds, minimize warping by using only

enough heat for 60-75% penetration.

3. For external buttwelds, make sure they are 100%

penetration with no internal cracks or crevices.

4. Do not weld internally then externally around the entire

circumference of the fittings.

5. Make sure there is little or no gap between pieces to be

welded.

6. Ensure that all surfaces affected by the heat of the weld,

especially the vacuum side, are purged properly with

inert gas.

FormoredetailsonTIGandothervacuumjoining

methods, contact MKS in Boulder, CO.

CAD Drawings

CAD drawings for the Series 23 buttweld line can be

downloaded from our website at: https://www.mksinst.com/

product/category.aspx?CategoryID=157. From there, select

the appropriate fitting and click to download the file. The

drawingsareavailablein*.DWGformatand*.DXFformat.

Ordering Information

To obtain delivery, technical, or applications

information, contact MKS at (800) 345-1967 (US only) or

(303) 449-9861. Or visit our website at www.mksinst.com.