SGC LABS can supply an extensive range of jointed glassware products utilising a conical, spherical or flat flange ground glass joint or screwthread joint.
Understand the different types of jointed glassware and when to use them.
Ground Glass Joints Technical Information
SGC LABS interchangeable conical joints are made to an accuracy that surpasses the requirements of ISO 383 & DIN 12242. A two stage grinding process ensures that the joints have a precision 1:10 taper and super-fine surface finish, resulting in joints that have an exceptionally good seal with a greatly reduced risk of joint seizure. The excellent surface finish also ensures that the joint will not leak and will be gas and vacuum tight. Conical ground glass joints are the most common type of joint and comprise a ground cone and socket. Joint sizes are described with two numbers e.g. 24/29
Ground Glass Joint Dimensions
- 24 – Diameter of the wide end of the ground joint (in millimetres)
- 29 – Length of the ground joint (in millimetres). Also known as the length of joint engagement.
We are able to supply a range of different conical joint sizes from 5/13 to 60/64.
Details on the types of joins we can supply are as follows:
Ground Glass Joint Size Chart
Most conical ground glass joints are manufactured to comply with the European ‘B’ length joint size requirements of ISO 383. Full length jointed glassware products are produced to American ASTM E-676 standard taper ground joint sizes.
European ‘B’ Length Joint Sizes:
| Size designation | Actual diameter of wide end (mm) | Actual diameter of narrow end (mm) | Nominal length of joint engagement |
|---|---|---|---|
| 7/16 | 7.5 | 5.9 | 16 |
| 10/19 | 10 | 8.1 | 19 |
| 12/21 | 12.5 | 10.4 | 21 |
| 14/23 | 14.5 | 12.2 | 23 |
| 19/26 | 18.8 | 16.2 | 26 |
| 24/29 | 24 | 21.1 | 29 |
| 29/32 | 29.2 | 26 | 32 |
| 34/35 | 34.5 | 31 | 35 |
| 40/38 | 40 | 36.2 | 38 |
| 45/40 | 45 | 41 | 40 |
| 50/42 | 50 | 45.8 | 42 |
| 55/44 | 55 | 50.6 | 44 |
| 60/46 | 60 | 55.4 | 46 |
American Standard Taper Joint Sizes
| Size designation | Actual diameter of wide end (mm) | Actual diameter of narrow end (mm) | Nominal length of joint engagement |
|---|---|---|---|
| 7/25 | 7.5 | 5 | 25 |
| 10/20 | 10 | 7 | 30 |
| 12/30 | 12.5 | 9.5 | 30 |
| 14/35 | 14.5 | 11 | 35 |
| 19/38 | 18.8 | 15 | 38 |
| 24/40 | 24 | 20 | 40 |
| 29/42 | 29.2 | 25 | 42 |
| 34/45 | 34.5 | 30 | 45 |
| 40/50 | 40 | 35 | 50 |
| 45/50 | 45 | 40 | 50 |
| 50/50 | 50 | 45 | 50 |
| 55/50 | 55 | 50 | 50 |
| 60/50 | 60 | 55 | 50 |
| 71/60 | 71 | 65 | 60 |
| 103/60 | 103 | 97 | 60 |
Using Screwthread Ground Glassware Joints
When using screwthreads it is important that the PTFE washer is fitted carefully and correctly. This is best achieved by opening out the washer to the correct diameter using a tapered former. This should be carried out with the silicone rubber ring and PTFE washer in position in the plastic cap as shown in Fig1.
Withdraw the tapered former and remove the rubber ring and washer from the cap. Fit each component separately to the fitting which is to be held, as shown in Fig 2, and screw the cap on to the thread. It is advisable that the ends of all fittings should be slightly tapered or fired in a Bunsen flame to remove sharp edges and produce a slight taper.