What is a groove and tongue flange?

A Tongue and Groove (T&G) flange is a matched pair of flanges — one has a raised ring (the tongue) and the mating flange has a matching machined depression (the groove). When bolted together, the tongue locates into the groove, fully confining the gasket inside the groove cavity. This prevents gasket blow-out, self-centres the joint, and provides superior leak integrity versus a raised face (RF) connection.

What is the difference between Large Tongue and Groove and Small Tongue and Groove flanges?

Per ASME B16.5, both types use the same principle but differ in the radial width of the tongue/groove ring. Large Tongue and Groove has wider tongue and groove dimensions (larger R/W for groove, larger T/Y for tongue), providing a bigger gasket seating area — used for standard process piping flanges. Small Tongue and Groove has a narrower ring width — typically used for vessel nozzle covers, pump covers, and compact joint designs where a smaller face is acceptable.

Can a tongue flange and groove flange be used with a raised face flange?

No. Tongue and groove flanges are a matched pair — a tongue flange must always mate with a groove flange of the same NPS, pressure class, and T&G type (large or small). A tongue flange mated to a raised face (RF) flange would result in the tongue bearing on the RF face rather than seating the gasket, creating an uneven bolt load and almost certain leakage.

What gaskets are used with tongue and groove flanges?

Tongue and groove flanges use gaskets sized to fit inside the groove — the gasket OD matches the groove OD and the gasket ID matches the groove ID. Common gasket types: spiral wound gaskets (with inner ring only — no centering ring needed as the groove self-centres), ring-type solid metal gaskets, and soft ring gaskets (PTFE, CAF, graphite). Because the gasket is confined on all four sides, significantly higher seating stress is achieved, enabling use of harder gasket materials.

What is the facing height of tongue and groove flanges per ASME B16.5?

Per ASME B16.5, the tongue height (which equals the groove depth) is 1.65 mm (1/16 inch) for Class 150 and Class 300 flanges — the same as the raised face height. For Class 400, 600, 900, 1500, and 2500 flanges, the tongue height is 6.35 mm (1/4 inch). This height is included in the minimum flange thickness for Class 150/300 but is additional to the minimum thickness for higher classes.

What is the difference between tongue and groove flanges and male-female flanges?

Both are paired face types with a projecting element on one flange and a matching recess on the other. The key difference is the gasket bearing area: in Tongue and Groove (T&G), the gasket contacts the bottom of the groove only (confined gasket). In Male and Female (M&F), the male face is flat and raised while the female face is a corresponding recess — the gasket sits on the male face and inside the female recess. T&G provides slightly better gasket confinement; M&F is more common for pipe flanges while T&G is more common for nozzle and heat exchanger connections.

What ASTM standard covers Carbon Steel Groove and Tongue flanges?

Carbon steel groove and tongue flanges are forged to ASTM A105 (standard service) or ASTM A350 LF2 (low-temperature service to −46°C / −50°F). The flange face is machined to ASME B16.5 T&G dimensions. Alloy steel flanges use ASTM A182 (F5, F9, F11, F22, F91). Stainless steel flanges use ASTM A182 (F304/304L, F316/316L, F321, F347, F904L). All supplied with EN 10204 3.1 material test certificates.

When should tongue and groove flanges be used instead of raised face flanges?

Tongue and groove flanges are specified over raised face (RF) flanges when: (1) the fluid is highly hazardous or toxic and gasket blow-out must be absolutely prevented; (2) very high differential pressure across the flange face requires confined gasket seating; (3) high fluid velocity could erode or wash out an exposed gasket; (4) the joint is on a heat exchanger channel cover or pump casing where repeated maintenance requires reliable re-assembly; (5) the process standard (such as API or company spec) mandates confined gasket faces for the service category.

Are groove and tongue flanges available in duplex stainless steel?

Yes. Tesco Steel supplies groove and tongue flanges in Duplex 2205 (ASTM A182 F51, UNS S31803/S32205) and Super Duplex 2507 (ASTM A182 F53, UNS S32750) and Zeron 100 (F55, UNS S32760). These are commonly specified for offshore oil and gas heat exchanger nozzles, seawater cooling systems, and desalination plant flanged connections where both high strength and chloride corrosion resistance are needed.

What is the surface finish requirement for tongue and groove flanges?

Per ASME B16.5, the groove and tongue contact face (where the gasket seats) is finished to 125–250 AARH (3.2–6.3 μm Ra) serrated finish for most gasket types. For spiral wound or sheet gaskets, 125–250 AARH concentric or phonographic serrations are standard. For solid metal ring gaskets, a smoother finish (63–125 AARH / 1.6–3.2 μm Ra) is required on the groove floor. The tongue height and groove depth tolerances are held to ±0.38 mm (±0.015 inch) per ASME B16.5.

Groove and Tongue Flanges Manufacturer in India

Tongue and Groove Flanges manufacturer India — ASME B16.5 SS 304 316 Inconel Monel

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What is a Groove and Tongue (T&G) Flange?

A Groove and Tongue flange (also written as Tongue and Groove or T&G) is a matched pair of flanges where one flange has a raised ring — the tongue — and the mating flange has a matching machined depression — the groove. When bolted together, the tongue seats precisely into the groove, fully confining the gasket within the groove cavity on all four sides.

This gasket confinement is the defining advantage of T&G flanges: unlike a raised face (RF) connection where the gasket is exposed at its outer edge, the T&G groove prevents the gasket from blowing out under high internal pressure or being eroded by high-velocity fluid flow. The joint also self-centres — the tongue locates the groove eliminating misalignment during assembly.

Tesco Steel & Engineering manufactures Groove and Tongue flanges per ASME B16.5 (½″–24″ NB, Class 150–2500) in both Large T&G and Small T&G configurations, across all standard materials from Carbon Steel ASTM A105 to exotic alloys including Hastelloy C276 and Titanium Grade 2. All flanges are ISO 9001:2015 certified with EN 10204 3.1 MTCs.

Critical Ordering Rule: Groove and Tongue flanges are a matched pair — a Tongue flange must always mate with a Groove flange of the same NPS, pressure class, T&G type (Large or Small), and dimensional standard. They cannot be mated to raised face, flat face, or ring type joint flanges. Always order both halves from the same specification.

Large T&G vs Small T&G — Key Differences

ASME B16.5 defines two distinct tongue and groove configurations that differ in the radial width of the tongue/groove ring:

Feature	Large Tongue & Groove	Small Tongue & Groove
Ring radial width	Wider — larger gasket seating area	Narrower — compact ring dimensions
Tongue OD (Y) vs Groove OD (W)	Larger Y and W values (see dimension table)	Smaller Y and W values (see dimension table)
Primary use	Standard process piping flanges, most common T&G application	Vessel nozzle covers, heat exchanger channel flanges, compact joints
Gasket area	Larger gasket area → lower seating stress required	Smaller gasket area → higher seating stress (good for harder gaskets)
ASME B16.5 reference	Tables E2.2 (tongue) and E2.1 (groove)	Tables E2.4 (tongue) and E2.3 (groove)
Interchangeability	Large tongue mates only with Large groove	Small tongue mates only with Small groove

How Tongue and Groove Flanges Work — Gasket Confinement Explained

Raised Face (RF) — Unconfined Gasket

Gasket sits on two raised faces — no lateral containment
Outer edge of gasket is exposed to line pressure
High pressure can cause gasket to extrude radially outward
Blow-out possible if bolting is inadequate or gasket degrades
Gasket alignment relies entirely on installer

Tongue & Groove (T&G) — Fully Confined Gasket

Gasket is confined on all four sides by the groove walls
Tongue seats into groove — self-centering joint
Gasket cannot blow out — groove walls physically prevent extrusion
Higher compression stress achieved on gasket face
Superior leak integrity for toxic, hazardous, or high-pressure service

T&G vs RF vs RTJ vs Male & Female — Face Type Comparison

Face Type	Gasket	Confinement	Self-Centering	Matched Pair?	Typical Use
Raised Face (RF)	Spiral wound / sheet	None — exposed outer edge	No	No — RF mates with RF	Standard general process service
Flat Face (FF)	Full-face rubber/PTFE	None	No	No — FF mates with FF	Mating with cast iron or glass-lined equipment
Tongue & Groove (T&G)	Ring gasket (SW, solid, soft)	Full — all four sides	Yes — tongue locates in groove	Yes — tongue + groove pair	Hazardous, toxic, high-pressure, high-velocity service
Male & Female (M&F)	Ring gasket	Partial — 3 sides	Yes	Yes — male + female pair	Pump nozzles, similar to T&G but more common in some APIs
Ring Type Joint (RTJ)	Solid metal ring (R/RX/BX)	Full — metal-to-metal	Yes — ring locates in groove	No — RTJ mates with RTJ (same ring groove)	High-pressure wellhead, Class 900+ HP/HT service

ASME B16.5 Groove and Tongue Flange Dimensions (mm)

Facing Height Notes (ASME B16.5):

Class 150 and Class 300: Tongue height (groove depth) = 1.65 mm (1/16″) — included in minimum flange thickness
Class 400, 600, 900, 1500, 2500: Tongue height (groove depth) = 6.35 mm (1/4″) — not included in minimum flange thickness
Tongue and groove minimum remaining lap thickness shall be no less than the nominal pipe wall thickness

Groove Flange dimensions diagram — ASME B16.5 R U W Z

Large Groove Flange Dimensions (ASME B16.5) — All dimensions in mm

Dimension key: R = Groove inner diameter (bore side) | U = Reference diameter | W = Groove outer diameter | Z = Groove depth

NPS	R (mm)	U (mm)	W (mm)	Z (mm)
½	35.05	25.40	36.57	23.87
¾	42.92	33.27	44.45	31.75
1	50.80	38.10	52.32	36.57
1¼	63.50	47.75	65.02	45.97
1½	73.15	53.84	74.67	52.32
2	91.94	73.15	93.72	71.37
2½	104.64	85.85	106.42	84.07
3	127.00	107.95	128.52	106.42
3½	139.70	120.65	141.22	119.12
4	157.22	131.82	158.75	130.04
5	185.67	160.27	187.45	158.75
6	215.90	190.50	217.42	188.97
8	269.74	238.25	271.52	236.47
10	323.85	285.75	325.37	284.22
12	381.00	342.90	382.52	341.37
14	412.75	374.65	414.27	373.12
16	469.90	425.45	471.42	423.92
18	533.40	488.95	534.92	487.42
20	584.20	533.40	585.72	531.87
24	692.15	641.35	693.67	639.82

Tongue Flange dimensions diagram — ASME B16.5 T U Y Z

Large Tongue Flange Dimensions (ASME B16.5) — All dimensions in mm

Dimension key: T = Tongue inner diameter | U = Reference diameter | Y = Tongue outer diameter | Z = Tongue height

NPS	T (mm)	U (mm)	Y (mm)	Z (mm)
½	35.05	25.40	36.57	23.87
¾	42.92	33.27	44.45	31.75
1	47.75	38.10	49.27	36.57
1¼	57.15	47.75	58.67	45.97
1½	63.50	53.84	65.02	52.32
2	82.55	73.15	84.07	71.37
2½	95.25	85.85	96.77	84.07
3	117.34	107.95	119.12	106.42
3½	130.04	120.65	131.82	119.12
4	144.52	131.82	146.05	130.04
5	172.97	160.27	174.75	158.75
6	203.20	190.50	204.72	188.97
8	254.00	238.25	255.52	236.47
10	304.80	285.75	306.32	284.22
12	361.95	342.90	363.47	341.37
14	393.70	374.65	395.22	373.12
16	447.54	425.45	449.32	423.92
18	511.04	488.95	512.82	487.42
20	558.80	533.40	560.32	531.87
24	666.75	641.35	668.27	639.82

Material Grades for Groove and Tongue Flanges

Material	ASTM / UNS Grade	Key Properties	Typical Service
Carbon Steel	ASTM A105	UTS 485 MPa, general purpose	Utility, steam, non-corrosive process
LTCS	ASTM A350 LF2	Impact tested to −46°C	LNG, cold utilities, cryogenic
Alloy Steel	ASTM A182 F5, F9, F11, F22, F91	Cr-Mo, high-temp strength to 650°C	Power generation, HP steam
SS 304 / 304L	ASTM A182 F304 / F304L	18Cr-8Ni, UTS 515 MPa	Mild corrosive, food, pharma
SS 316 / 316L	ASTM A182 F316 / F316L	16Cr-10Ni-2Mo, pitting resistant	Marine, chemical, chloride environments
SS 321 / 347	ASTM A182 F321 / F347	Ti or Nb stabilised, sensitisation-resistant	High-temperature steam, boilers
SS 310	ASTM A182 F310	25Cr-20Ni, high-temp oxidation	Furnaces, high-temperature gas
904L	ASTM A182 F904L (UNS N08904)	20Cr-25Ni-4.5Mo-1.5Cu	H₂SO₄, phosphoric acid, seawater
Duplex 2205	ASTM A182 F51 (UNS S31803/S32205)	PREN ≥ 35, UTS 620 MPa	Offshore, desalination, heat exchangers
Super Duplex 2507	ASTM A182 F53 (UNS S32750)	PREN ≥ 40, UTS 795 MPa	High-chloride, deep offshore
Monel 400	ASTM B564 (UNS N04400)	67Ni-30Cu, HF acid resistant	Hydrofluoric acid, marine, brine
Inconel 625	ASTM B564 (UNS N06625)	21Cr-9Mo-3.65Nb, UTS 830 MPa	Subsea, aggressive acid, aerospace
Incoloy 825	ASTM B564 (UNS N08825)	21Cr-38Ni-3Mo-2.2Cu, SCC resistant	Sour gas, phosphoric/sulphuric acid
Hastelloy C276	ASTM B564 (UNS N10276)	16Cr-16Mo-4W, broadest acid resistance	HCl, H₂SO₄, wet chlorine, FGD
Hastelloy C22	ASTM B564 (UNS N06022)	21Cr-13Mo-3W, oxidising + reducing	Mixed acid, pharma, chlorination
Cupro Nickel 90/10	C70600 (UNS)	Biofouling resistant, seawater	Naval, offshore, condenser nozzles
Titanium Gr. 1 / Gr. 2	ASTM B381 F-1 / F-2	CP titanium, excellent seawater and halide resistance	Seawater, bleach plants, wet chlorine
Nickel 200 / 201	UNS N02200 / N02201	99.6% Ni, caustic resistant	Caustic soda production, food processing

Applications of Groove and Tongue Flanges

Industry	Typical Application	Why T&G is Specified	Material
Oil & Gas	Sour gas wellhead nozzles, HP separator flanges	Gasket blow-out prevention in HP H₂S service	A182 F316L, F51, Inconel 625
Petrochemical	Reactor manways, column nozzles, heat exchanger channel covers	Confined gasket for toxic hydrocarbon service	A105, A182 F316L, Hastelloy C276
Power Generation	HP/HT steam generator nozzles, turbine inlet flanges	High sealing integrity at elevated pressure and temperature	A182 F11, F22, F91
Chemical Processing	Acid reactor flanges, column reboiler connections	Gasket confinement prevents acid leakage/splash hazard	A182 F316L, Hastelloy C276, Titanium Gr.2
Offshore & Marine	Subsea wellhead flanges, seawater heat exchanger nozzles	High-integrity seal in deep-sea HP service	Duplex F51, Super Duplex F53, CuNi C70600
Pharmaceutical	Sterile process vessel nozzles, CIP system connections	No gasket-face gap to harbour contamination; repeatable reassembly	A182 F316L (ASME-BPE), Hastelloy C22
Pulp & Paper	Bleach plant digester nozzles, chlorine dioxide system flanges	Contained seal for corrosive bleaching chemical service	A182 F316L, Hastelloy C276, Titanium Gr.2
Cryogenic / LNG	LNG cold box flanges, cryogenic storage vessel nozzles	Gasket confinement prevents seal failure during thermal cycling	A350 LF2, A182 F304L, Monel 400

Standards & Specifications

Category	Standard	Scope
Dimensional	ASME B16.5	Pipe flanges and flanged fittings — Class 150–2500, incl. T&G dimensions (Appendix E)
Dimensional	ASME B16.47	Large diameter flanges NPS 26–60, Series A and B
Dimensional	MSS SP-44	Steel pipeline flanges, alternate large-diameter standard
Dimensional	EN 1092-1	European flanges — steel, PN 2.5–400
Dimensional	DIN 86029	DIN tongue and groove flanges for marine / ship applications
Material — CS	ASTM A105	Carbon steel forgings for piping components
Material — LTCS	ASTM A350 LF2	Low-temperature carbon steel forgings
Material — Alloy/SS	ASTM A182	Alloy and stainless steel flanged fittings and forgings
Material — Nickel Alloys	ASTM B564	Nickel and nickel alloy forgings
Material — Titanium	ASTM B381	Titanium and titanium alloy forgings
Gaskets	ASME B16.20	Metallic gaskets for pipe flanges — spiral wound, ring joint
Inspection	EN 10204 3.1 / 3.2	Material test certificate — 3.1 works certification, 3.2 third-party witness
Piping Code	ASME B31.3	Process piping design and material requirements
Pressure Vessel	ASME VIII Div. 1	Vessel nozzle flange design basis

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Quick Specifications

Standard	ASME B16.5, B16.47, EN 1092-1, DIN 86029
Types	Large T&G, Small T&G
Size Range	½″ – 24″ NB (DN 15 – DN 600)
Pressure Class	150, 300, 600, 900, 1500, 2500
PN Rating	PN 6 – PN 400
Tongue Height	1.65 mm (Cl.150/300) / 6.35 mm (Cl.400+)
Finish	125–250 AARH serrated
Cert	EN 10204 3.1 / 3.2

Flange Face Types

Raised Face (RF)
Flat Face (FF)
Groove & Tongue (T&G) ← You are here
Male & Female (M&F)
Ring Type Joint (RTJ)

Specify T&G Flanges When:

Fluid is toxic or highly hazardous
Gasket blow-out must be prevented
Very high internal pressure
High-velocity flow could erode gasket
Heat exchanger channel covers
Pump and compressor nozzles
Repeated maintenance with consistent re-seal

Gasket Selection for T&G

Spiral wound (no CR): Standard process, groove self-centres
Solid metal ring: HP/HT service, Class 900+
Graphite ring: High-temp non-oxidising service
PTFE ring: Chemical/food service, Cl.150–300
CAF ring: Steam, general utility

Note: No centering ring needed on spiral wound gaskets — groove provides centring.

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Testing & Inspection

Dimensional check (tongue/groove depth)
Surface roughness measurement (Ra)
Hardness testing (Brinell / Rockwell)
Hydrostatic pressure test
PMI (XRF) — alloy verification
Dye penetrant (PT) inspection
Magnetic particle (MT) for CS flanges
EN 10204 3.1 / 3.2 MTCs

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