Carbon, Stainless & Alloy Steel Flanges

Tubineu supplies forged steel flanges for pressure piping and equipment connections requiring controlled dimensions, pressure-temperature integrity, and full material traceability. The range typically includes weld neck, slip-on, blind, socket weld, threaded, and lap joint types in carbon steel, stainless steel, duplex stainless steel, and alloy steel grades for refinery, petrochemical, power generation, offshore, water treatment, LNG, and general process applications. Flanges are supplied to recognized dimensional and material specifications with project-specific scope for facing type, pressure class, heat treatment, inspection, marking, and certification.

Flange Types, Dimensions & Standards

Steel flanges are forged or machined components used to create bolted, gasketed joints between pipe, valves, pumps, and pressure-retaining equipment. Standard dimensional requirements are generally specified to ASME B16.5 for NPS 1/2 through NPS 24, including flange dimensions, facing details, bolting, tolerances, and pressure-temperature ratings, while larger diameters may be specified to ASME B16.47. Common pressure classes include Class 150, 300, 400, 600, 900, 1500, and 2500, with facing configurations such as raised face, flat face, and ring type joint selected according to service severity and gasket design. Flanges are matched to the adjoining pipe outside diameter, wall schedule, and service conditions so that bore alignment, weld preparation, and pressure class remain consistent throughout the piping system.

Carbon Steel Flanges

Carbon steel flanges are widely specified for general industrial, moderate-temperature, and high-temperature pressure service where strength, weldability, and cost efficiency are key selection factors. Standard forged grades are matched to carbon steel piping systems used in refineries, utilities, oil and gas, and water service, with material choice based on design temperature, minimum design metal temperature, required toughness, and pressure class. Supply condition may include normalized or otherwise heat-treated forgings in accordance with the governing ASTM specification and project requirements

Size:

1/2" through 60"

Schedule Range:

STD, 40, XH, XS, 60, 80, 100, 120, 140, 160, XXH, XXS

Common material specifications: 

ASTM A105 

For ambient and elevated-temperature service

ASTM A350 LF2 

For low-temperature service with impact testing

ASTM A694 F52

ASTM A694 F60

ASTM A694 F65

ASTM A694 F70 

For higher-strength pipeline and transmission applications.

Common flange types and faces: 

Weld neck

Slip-on 

Blind

Socket weld

Threaded

Lap joint 

Long Weld neck

Spectacle Blinds 

With raised face, flat face, or ring type joint facing as required by the piping class and gasket selection

Dimensional and rating standards: 

ASME B16.5 

EN1092:1

DIN

BS4504

ASME B16.48 

For NPS 1/2 through NPS 24 

ASME B16.47 

BS 3293

For larger diameters where applicable

Pressure classes generally from 150 through 2500 and bore matched to the adjoining pipe schedule

Bore and facing details are coordinated with the piping class and corrosion allowance philosophy

Inspection and testing: 

Visual and dimensional inspection

Mechanical verification to the forging specification

Chemical analysis

Impact testing for LF2, 

and optional PMI, UT, MT, hardness testing, and witness inspection according to project requirements

Typical Service: 

General process piping

Utility systems

Oil and gas installations

Petrochemical piping

Power plants

Water and steam service

Low-temperature systems

Pump and valve connections

Structural and mechanical 

Pipeline applications requiring robust bolted joints

Stainless Steel Flanges

Stainless steel flanges are selected where corrosion resistance, hygienic performance, and metallurgical stability are critical to reliable service. Austenitic grades are commonly used for general chemical and utility duty, while molybdenum-bearing and duplex grades are preferred for chloride-containing environments, marine exposure, and more demanding corrosion conditions. Material selection is generally aligned with process chemistry, operating temperature, cleaning requirements, and any post-weld corrosion performance criteria.

Size:

1/2" through 60"

Schedule Range:

10s,STD, 40s, XH, XS, 60s, 80s, 100s, 120s, 140s, 160s, XXH, XXS

Common material specifications: 

ASTM A182 F304/F304L

ASTM A182 F316/F316L

ASTM A182 F321

ASTM A182 F347 

For austenitic stainless steel flanges 

ASTM A182 F51

ASTM A182 F53

ASTM A182 F55 

For duplex and super duplex grades used where higher strength and improved chloride resistance are required

Common flange types and faces: 

Weld neck

Slip-on

Blind

Socket weld

Threaded

Lap joint 

With raised face, flat face, or ring type joint facings selected to suit corrosion service, maintenance needs, and gasket design

Dimensional and rating standards: 

ASME B16.5

EN1092:1

DIN

BS4504

ASME B16.48 

For NPS 1/2 through NPS 24 

ASME B16.47

BS3293 

For larger diameters where applicable

Pressure classes generally from 150 through 2500 and bore matched to the adjoining pipe schedule

Bore and facing details are coordinated with the piping class and corrosion allowance philosophy

Inspection and testing:

Visual and dimensional inspection

Mechanical verification to the forging specification

Chemical analysis

Solution annealing or applicable heat treatment control

and optional PMI, ferrite control, dye penetrant testing, UT, and intergranular corrosion testing where specified

Typical service:

Chemical processing

Marine service

Water treatment

Food and beverage systems

Pharmaceuticals

Offshore

Chloride-rich environments

Desalination

Services requiring corrosion-resistant bolted connections

Available Options

Flange types: 

Weld neck, slip-on, blind, socket weld, threaded, lap joint, reducing, and selected special-purpose flanges subject to specification and size range.

Size and rating scope: 

Standard sizes from NPS 1/2 to NPS 24 to ASME B16.5, with larger diameters to ASME B16.47 where required, across pressure classes typically from 150 through 2500.

Facing options: 

Raised face, flat face, and ring type joint facings selected according to gasket type, bolting requirements, and service severity.

Testing and NDE options: 

Dimensional inspection, visual examination, PMI, hardness testing, UT, MT, PT, ferrite testing, impact testing, and third-party inspection as specified by code or purchaser requirements.

Supply condition and traceability: 

Heat treatment in accordance with the material specification, permanent marking, heat number traceability, flange marking to the applicable standard, and material test certificates to EN 10204 3.1 or equivalent documentation on request.

Project support:
Third-party inspection, customer witness points, special marking, export packing, gasket and bolting coordination, and documentation packs aligned with EPC and end-user specifications.

For project inquiries, Tubineu can support technical review of flange specifications covering material grade, flange type, facing, pressure class, dimensional standard, inspection scope, and documentation requirements for carbon steel, stainless steel, and alloy steel flanges