Your contact for

Ring-Joints

Your contact for

Ring-Joints

Demands on form accuracy and surface quality are high

Ring-Joints RTJ

Ring-Joint (RTJ) gaskets are made from metallic materials. The requirements in terms of dimensional accuracy and surface quality are therefore high. This relates to both the gasket and the sealing section of the flange. The necessary surface quality depends substantially on the Brinell hardness of the gasket material The relationship RZ [µm] < 300/HB provides a useful indication. A distinction is made between two kinds of ring joint gaskets and two different calculation methods are therefore used:

 

1. RTJ gaskets with osculating radius

a) The convex octagonal RTJ gaskets, Profile AR 13, in which the convex cone case surfaces of the gasket are pressed against the even cone case surfaces of the groove when tensioned.

b) The oval ring-joint gasket, Profile A11, in which the circular surface is pressed against the cone case surfaces of the groove.

The sealing surface pressure increases or decreases to a lesser extent in response to any change in the bolt load.

 

2. RTJ gaskets with flat sealing surfaces

The octagonal RTJ gasket, Profiles A13 and A14, are flat gaskets in which the sealing surfaces are two cone case surfaces. The projection in the direction of the bolting force bG = b1 + b2 should be set as the sealing surface width.
The sealing surface pressure increases or decreases proportionally in response to any change in the bolt load.

The application thresholds values of oval octagonal RTJ gaskets can be more accurately calculated in relation to material, diameter, pressure, temperature and the surface pressure limits. Here the fictitions sealing characteristic values in accordance with AD are replaced with the values of σv and σ .ϑ Ring joint gaskets in accordance with API and ASME standards are mainly used in the petrochemical industry and in refineries as a reliable gasket for production pipelines. We are permitted to give our products the API Monogram. This guarantees that our products meet the latest API standards. It should be noted that in Profile A12 the flanges have metalto-metal contact. Profile AR13 with convex sealing surfaces. Ring joint gaskets can be produced as blind gaskets in Profile A11S, A13S etc. or as blind spectacle gaskets in Profile A11BS, A13BS (see Blind Gaskets).

Code designationMaterial no.Hardness (HB)US-Type AISICode
Pure iron, e.g. Armco1.100390-100Soft-IronD
Stw24mod-90-100Soft-IronD
Low-carbonsteel-120Low-Carbon-SteelS
13 CrMo 4 41.7335Ca. 160-7335
12 CrMo19 5 mod1.7362 modCa. 130501F5
X6 Cr 131.4000Ca. 160410S410
X5 CrNi 18 101.4301Ca. 160304S304
X5 CrNiMo 17 12 21.4401Ca. 160316S316
X6 CrNiTi 18 101.4541Ca. 160321S321
X6 CrNiNb 18 101.4550Ca. 160347S347
X6 CrNiMoTi 17 12 21.4571Ca. 160316 Ti316 Ti

Gasket cross-section

With the addition of a protective ring made from sheet metal to Profile F22, disruptive turbulence and accretions are avoided. At small edge widths the protective gaskets are symmetrical, at larger edge widths they are centred on one side. We can supply soft-iron compensating caps for damaged grooves, such as Profile AK11, AK12, AK13, AK14. For a complete estimate on sealing flange connections, our efficient sealing estimate service is available.

ProfileA11, A11S, A11BS, A12, A13, A13S, A13BS, AR13, AR13S, AR13BS, A14
MaterialsIron 1.1003 Stw24modHeat-resistant mild steel 1.5415Heat-resistant mild steel 1.7362Stainless Steel 1.4541Stainless Steel 1.4828Carbon steel copper-platedStainless steel 1.4541silver-platedCopper2.0090Monel 2.4360
Recommended max. roughness of the flange surfacesµmvon
bis
3,2
6,3
3,2
6,3
3,2
6,3
1,6
3,2
1,6
3,2
3,2
6,3
6,3
12,5
3,2
6,3
3,2
6,3
Surface pressure limits for 20 °CN/mm2σv
σϑ
235
525
300
675
400
900
335
750
400
900
135
600
100
750
135
300
260
660
E modulus at 20 °CkN/mm2 210210210200200210200128178
Surface pressure limits for 300 °CN/mmσv
σϑ
235
315
300
585
400
730
400
750
400
750
135
390
100
630
135
150
260
650
E modulus at 300 °CkN/mm2 185185190186186185186114175