THREADED FLANGES

Super Industries

Global Manufacturer of Heavy & Custom Engineered Fasteners for Oil & Gas, Power & EPC Contractors.

1. Industry Context & System Relevance

In industrial piping systems, Threaded Flanges serve as a mechanically assembled pressure-connection interface designed for joining threaded pipe ends, valves, strainers, instrumentation branches, and auxiliary equipment without welding.

These flanges are primarily selected where:

• welding is operationally restricted
• hot work permits are difficult to obtain
• line modifications are expected during maintenance
• small-bore piping requires fast assembly
• temporary or modular installations are preferred

Threaded flange connections remain widely used across:

• oil & gas gathering lines
• refinery utility systems
• power plant auxiliary services
• petrochemical secondary lines
• compressed air systems
• firefighting and hydrant networks
• instrument impulse lines
• water and utility piping

Their principal advantage lies in providing a pressure-retaining joint without fusion welding, making them particularly suitable for low-to-medium pressure services and hazardous areas.

Application in Oil & Gas Systems

Within upstream and downstream facilities, threaded flange assemblies are commonly applied in:

• chemical injection lines
• fuel oil transfer systems
• instrument tubing transitions
• low-pressure hydrocarbon services
• nitrogen and air utility lines
• drain and vent headers

In brownfield modifications and shutdown maintenance, threaded flanges are frequently preferred because they reduce:

• welding setup time
• welder qualification dependency
• NDT requirements for field joints
• post-weld heat treatment concerns

This directly improves maintenance turnaround efficiency.

Role in Refineries & Petrochemical Plants

Refineries often operate under strict hot-work controls due to hydrocarbon presence.

In such areas, Threaded Flanges provide an effective connection method for:

• temporary bypass lines
• analyzer connections
• steam tracing auxiliaries
• sample take-off points
• low-pressure chemical circulation loops

Because no arc welding is required, installation risk in volatile atmospheres is significantly reduced.

Use in Power Plants

Thermal and combined-cycle power plants utilize threaded flange systems for:

• service water lines
• fuel gas auxiliaries
• instrument air systems
• drain headers
• lubrication oil piping

However, use in high-temperature steam mains is generally avoided due to stress concentration risks associated with threaded joints.

Fire Protection & Utility Systems

Threaded flange assemblies are extensively used in:

• sprinkler systems
• fire water ring mains
• jockey pump connections
• hydrant branches
• municipal water services

These services typically operate at moderate pressure ranges where threaded joints remain practical and code-compliant.

Why Threaded Connections Are Used

The engineering logic behind using threaded flanges is primarily based on service practicality.

A. Low-Pressure Systems

For systems operating below the threshold where welded joints become structurally necessary, threaded flanges offer sufficient sealing and load resistance.

Typical applications include:

• Class 150
• Class 300
• limited Class 600 services
• specialized Class 1500 small-bore lines

depending on medium, temperature, and cyclic loading.

B. Non-Weld Applications

Threaded flange joints are specified where welding is undesirable because of:

• flammable environment
• material metallurgical sensitivity
• field accessibility constraints
• maintenance downtime limitations

This is especially relevant for retrofit projects.

C. Hazardous Environments (No Hot Work Zones)

Many hydrocarbon plants impose restricted zones where hot work is prohibited.

In such conditions, threaded connections enable safe mechanical installation.

Examples include:

• offshore platforms
• gas compression stations
• solvent handling plants
• tank farm utilities

D. Maintenance-Friendly Installations

Since the connection is detachable, threaded flanges support:

• valve replacement
• inline equipment servicing
• branch isolation
• periodic inspection access

This makes them suitable for maintenance-intensive systems.

Comparison: Threaded vs Welded vs Other Flange Types

Connection Type	Welding Required	Pressure Capability	Maintenance Ease	Leak Risk
Threaded Flanges	No	Low to Medium	High	Moderate
Slip-On Flanges	Yes	Medium	Medium	Low
Weld Neck Flanges	Yes	High	Medium	Very Low
Socket Weld	Yes	Medium to High	Medium	Low

Threaded vs Weld Neck

A weld neck flange transfers axial and bending loads through a tapered hub and butt weld.

A threaded flange transfers load through:

• thread shear
• flank compression
• sealing interference

Therefore, threaded flanges are generally less suitable for:

• high vibration systems
• thermal cycling services
• high-pressure steam lines

2. Technical Definition

A Threaded Flange is an internally threaded flange fitting designed to mate with an externally threaded pipe end, creating a pressure-retaining joint without welding.

It is also commonly referred to as:

• screwed flange
• female threaded flange
• threaded pipe flange

The internal bore contains precision-machined threads matching the pipe standard.

Construction Definition

The flange consists of:

• flange face
• bolt circle
• hub section
• internally threaded bore

The pipe is rotated into the flange bore until full thread engagement is achieved.

No Welding Required

This is the defining engineering characteristic.

The joint relies on:

• mechanical thread engagement
• torque-induced interference
• thread sealant integrity

rather than welded fusion.

This significantly simplifies field assembly.

Thread Standards

A. NPT – National Pipe Thread

The most widely used standard in industrial piping is:

ASME B1.20.1 – NPT

NPT threads are tapered.

This taper creates progressive interference as the pipe advances into the flange.

The sealing is achieved through:

• flank pressure
• deformation at thread crests
• sealant filling micro-gaps

B. BSPT / BSPP

For export markets, threaded flanges may also be supplied in:

• BSPT – British Standard Pipe Taper
• BSPP – British Standard Pipe Parallel

These are frequently used in:

• Europe
• Middle East
• Southeast Asia

Tapered vs Parallel Threads

Thread Type	Geometry	Sealing Method
Tapered	Conical	Interference sealing
Parallel	Straight	Gasket / sealant dependent

Tapered threads provide better inherent sealing behavior.

Parallel threads require greater dependence on sealants or secondary sealing faces.

3. Engineering & Sealing Principle

The sealing performance of threaded flanges depends on the mechanics of thread engagement.

Thread Engagement Mechanics

As the male threaded pipe enters the flange thread, the helical surfaces begin load transfer.

The thread acts as a continuous inclined plane wrapped helically around the pipe axis.

Load is distributed along multiple engaged thread turns.

This creates:

• axial retention
• radial interference
• pressure containment

Helical Load Distribution

The load path follows the thread helix.

The first engaged threads generally experience the highest stress.

Typical load distribution:

• first thread: 30–35%
• second thread: 20–25%
• remaining threads: progressively lower

This is why machining accuracy is critical.

Sealing via Thread Interference

In tapered threads, sealing occurs through controlled interference.

As torque increases:

• flank contact pressure rises
• leak paths reduce
• thread root clearance decreases

Sealants such as:

• PTFE tape
• anaerobic thread compound
• liquid sealant paste

are used to block residual micro-leak paths.

Leak Paths in Threaded Joints

Potential leak paths include:

• crest-to-root clearances
• imperfect flank contact
• thread damage
• pitch mismatch
• galling in stainless steel

This makes thread tolerance control essential.

Role of Thread Pitch

Thread pitch directly affects:

• load transfer length
• sealing contact area
• assembly torque response

Finer pitch generally provides:

• improved sealing
• higher flank engagement area

but may be more sensitive to contamination.

Taper Angle Behavior

For NPT threads, taper is typically:

1 in 16 on diameter

This taper creates progressive sealing compression.

The further the pipe is tightened, the stronger the sealing interference becomes.

Engineering Limitations

Threaded flange systems must be evaluated carefully for service conditions.

A. Vibration

Continuous vibration can lead to:

• thread loosening
• flank wear
• fatigue crack initiation
• leakage

Hence, they are not preferred for rotating equipment discharge lines.

B. Pressure Constraints

Compared with welded joints, threaded connections have lower pressure reliability.

Pressure cycling increases risk of:

• sealant breakdown
• thread deformation
• leakage

C. Temperature Effects

Elevated temperatures can cause:

• thermal expansion mismatch
• relaxation of thread preload
• sealant degradation

This is particularly critical above 400°C service.

4. Applicable Standards (ASME / ASTM / DIN / ISO)

The design, manufacture, inspection, and application of Threaded Flanges are governed by internationally recognized standards that ensure dimensional uniformity, pressure integrity, and interchangeability across global EPC projects.

ASME Standards

ASME B16.5 – Pipe Flanges and Flanged Fittings

This is the primary governing standard for Threaded Flanges up to NPS 24.

It defines:

• pressure-temperature ratings (Class 150 to Class 1500)
• dimensional requirements (OD, thickness, bolt circle)
• facing types (RF, FF)
• tolerances
• marking requirements

Threaded flanges under ASME B16.5 are designated as:

• Class 150
• Class 300
• Class 600
• Class 900
• Class 1500

The standard ensures compatibility with mating flanges and bolting systems.

ASME B1.20.1 – Pipe Threads (NPT)

This standard governs:

• thread geometry
• taper angle (1:16)
• pitch
• thread engagement length
• gauge requirements

It ensures sealing capability through controlled interference.

ASTM Material Standards

Material selection for Threaded Flanges is governed by ASTM specifications, defining:

• chemical composition
• mechanical properties
• heat treatment requirements
• testing procedures

Common standards include:

• ASTM A105 – Carbon steel forgings
• ASTM A350 LF2 – Low-temperature carbon steel
• ASTM A182 – Alloy and stainless steel forgings

DIN / EN Standards

European projects often require compliance with:

• EN 1092-1 – Flanges and flanged connections
• DIN threaded flange equivalents (legacy systems)

Thread compatibility must be aligned with:

• BSPT / BSPP thread standards

ISO Thread Standards

ISO standards define:

• metric thread systems
• international compatibility
• tolerance classifications

Used primarily for non-NPT export requirements.

Standard Mapping to Engineering Selection

Requirement	Governing Standard
Dimensional conformity	ASME B16.5 / EN 1092-1
Thread geometry	ASME B1.20.1 / BSP standards
Material properties	ASTM A105 / A182 / A350
Pressure rating	ASME B16.5
Inspection & testing	ASTM + project specifications

5. Material & Grade Options

Material selection for Threaded Flanges is based on:

• operating pressure
• service temperature
• corrosion environment
• fluid compatibility
• project specifications

Carbon Steel Grades

ASTM A105

• Standard material for ambient and moderate temperature services
• Suitable for oil & gas, water, and utility lines
• Good machinability and strength

ASTM A350 LF2

• Designed for low-temperature applications
• Improved toughness at sub-zero conditions
• Used in cryogenic and cold-weather installations

Stainless Steel Grades

ASTM A182 F304

• General corrosion resistance
• Suitable for water, mild chemicals, and food-grade systems

ASTM A182 F316

• Enhanced corrosion resistance due to molybdenum
• Suitable for marine, chemical, and chloride environments

Alloy Steel Grades

ASTM A182 F11

• Chromium-molybdenum alloy
• Suitable for moderate high-temperature services

ASTM A182 F22

• Higher creep resistance
• Used in elevated temperature and pressure systems

Duplex / Super Duplex Stainless Steel

• Higher strength than austenitic stainless steel
• Excellent resistance to stress corrosion cracking
• Used in offshore, subsea, and aggressive chemical environments

Material Comparison Table (Engineering Reference)

Grade	Yield Strength (MPa)	Tensile Strength (MPa)	Temperature Range	Corrosion Resistance	Typical Industry Use
ASTM A105	~250	~485	-29°C to 425°C	Low	Oil & gas, water lines
ASTM A350 LF2	~250	~485	-46°C to 345°C	Low	Low-temperature systems
ASTM A182 F304	~205	~515	-196°C to 870°C	Moderate	Food, water, chemicals
ASTM A182 F316	~205	~515	-196°C to 870°C	High	Marine, chemical
ASTM A182 F11	~275	~515	Up to ~540°C	Moderate	Power plants
ASTM A182 F22	~415	~585	Up to ~600°C	Moderate	High-temp systems
Duplex SS	~450	~620	-50°C to 300°C	Very High	Offshore, subsea

6. Heat Treatment Information

Heat treatment ensures that Threaded Flanges achieve required mechanical properties, dimensional stability, and metallurgical structure.

Normalizing

Applicable to carbon steel:

• refines grain structure
• improves uniformity
• enhances mechanical strength

Quenching & Tempering

Used for alloy steels:

• increases strength and toughness
• improves fatigue resistance
• reduces brittleness

Stress Relieving

Performed after machining:

• reduces residual stresses
• prevents distortion during service
• stabilizes dimensional accuracy

Solution Annealing (Stainless Steel)

• dissolves carbides
• restores corrosion resistance
• improves ductility

Rapid cooling prevents sensitization.

Hardness Control

Hardness is maintained within specified limits to:

• avoid brittle failure
• ensure machinability
• prevent thread galling

Impact Testing (Charpy V-Notch)

Required for low-temperature services:

• measures toughness
• ensures resistance to brittle fracture

7. Manufacturing Process

The production of Threaded Flanges follows a controlled sequence to ensure dimensional accuracy and pressure integrity.

Raw Material Inspection

Incoming material is verified for:

• chemical composition (via mill test certificate)
• mechanical properties
• traceability

Forging / Bar Stock Preparation

Flanges are produced by:

• open-die forging
• closed-die forging
• machining from rolled bar (small sizes)

Forging improves:

• grain flow alignment
• mechanical strength
• structural integrity

Rough Machining

Initial machining includes:

• outer diameter turning
• hub shaping
• bore preparation

Thread Machining

Critical stage involving:

• CNC threading or tapping
• precision control of pitch and taper
• adherence to ASME B1.20.1

Thread quality directly affects sealing performance.

Facing & Drilling

• flange face machining (RF/FF)
• bolt hole drilling
• surface finish control

Heat Treatment

Performed based on material grade:

• normalizing
• quenching & tempering
• solution annealing

Surface Finishing

Application of coatings based on project requirement.

Marking & Traceability

Each flange is marked with:

• material grade
• heat number
• pressure class
• manufacturer identification

Ensures full traceability.

Thread Accuracy Control

Threads are verified using:

• calibrated gauges
• pitch measurement tools
• taper verification

Gauge Inspection (Go / No-Go)

Thread acceptance is validated using:

• Go gauge → ensures proper engagement
• No-Go gauge → prevents oversize threads

This ensures field compatibility and sealing reliability.

Surface Finish Options

Surface protection is selected based on environmental exposure and service conditions.

Black Oxide

• minimal corrosion protection
• used for indoor or controlled environments

Phosphate Coating

• improves corrosion resistance
• enhances lubricant retention

Zinc Plating

• provides moderate corrosion protection
• used in utility applications

Hot-Dip Galvanizing

• thick zinc coating
• suitable for outdoor and marine environments
• requires thread tolerance compensation

PTFE Coating

• reduces friction
• improves sealing
• provides chemical resistance

Passivation (Stainless Steel)

• removes surface contaminants
• enhances corrosion resistance
• improves oxide layer stability

Surface Finish vs Thread Integrity

Surface treatment must not:

• distort thread geometry
• reduce engagement accuracy
• create excessive coating thickness

Threaded areas require controlled coating thickness to maintain tolerance.

A. Technical Dimension Tables (ASME B16.5 Reference)

The dimensional configuration of Threaded Flanges is governed primarily by ASME B16.5. The following table provides representative dimensional data for commonly used sizes and pressure classes. Final dimensions must always be verified against the latest revision of the applicable standard and project specifications.

Class 150 – Threaded Flanges (Raised Face)

Nominal Pipe Size (NPS)	Thread Size (NPT)	Flange OD (mm)	Thickness (mm)	Bolt Circle (mm)	No. of Holes	Pressure Class
1/2”	1/2”	89	11.2	60.3	4	150
1”	1”	108	12.7	79.4	4	150
2”	2”	152	15.9	120.7	4	150
4”	4”	229	23.9	190.5	8	150
6”	6”	279	25.4	241.3	8	150
8”	8”	343	28.6	298.5	8	150

Class 300 – Threaded Flanges

NPS	Thread Size	Flange OD (mm)	Thickness (mm)	Bolt Circle (mm)	No. of Holes
1/2”	1/2”	95	14.2	66.7	4
1”	1”	124	17.5	88.9	4
2”	2”	165	20.6	127	8
4”	4”	254	31.8	200	8
6”	6”	318	36.6	269.9	12

Facing Types

Facing Type	Description	Application
Flat Face (FF)	Full face contact	Cast iron systems, low pressure
Raised Face (RF)	Elevated sealing surface	Standard industrial service

B. Pressure Rating Table (ASME B16.5)

Pressure ratings for Threaded Flanges vary with material and temperature. The following provides indicative values at ambient temperature for carbon steel (ASTM A105).

Pressure Class vs Pressure

Class	Pressure (PSI)	Pressure (MPa)
150	285 PSI	1.96 MPa
300	740 PSI	5.10 MPa
600	1480 PSI	10.20 MPa
900	2220 PSI	15.30 MPa
1500	3705 PSI	25.55 MPa

Temperature Influence

Pressure ratings reduce with increasing temperature due to material strength degradation.

Example:

• At 400°C → allowable pressure significantly decreases
• Material selection becomes critical

C. Torque Chart

Although Threaded Flanges rely on pipe threading, flange bolting still governs joint sealing between mating flanges.

Torque Values (Indicative)

Bolt Size	Grade	Dry Torque (Nm)	Lubricated Torque (Nm)
M12	Class 8.8	85	65
M16	Class 8.8	210	160
M20	Class 8.8	410	320
M24	Class 8.8	710	550
M20	Class 10.9	580	450
M24	Class 10.9	1000	780
3/4”	ASTM A193 B7	380	290
1”	ASTM A193 B7	750	580

Torque Considerations

• Lubrication reduces friction → lower torque required
• Over-tightening can cause:
  • gasket crushing
  • bolt yielding
• Under-tightening leads to leakage

D. Thread Engagement & Stress Calculation Guide

The integrity of Threaded Flanges depends significantly on thread shear strength and engagement length.

Thread Shear Area Formula

   

Where:

• ( A_s ) = shear area
• ( d_m ) = mean thread diameter
• ( L_e ) = length of engagement

Load Capacity

   

Where:

• ( F ) = axial load capacity
• ( \tau_{allow} ) = allowable shear stress

Sample Engineering Calculation

Assume:

• Mean diameter = 50 mm
• Engagement length = 25 mm
• Allowable shear stress = 120 MPa

Shear area:

   

Load capacity:

   

Failure Prevention Logic

To prevent failure:

• ensure sufficient thread engagement length
• avoid over-machining of threads
• maintain proper tolerance class
• avoid repeated assembly cycles

E. Yield Strength Chart

Material yield strength directly affects allowable stress in Threaded Flanges.

General trend:

• Carbon steel → moderate strength
• Stainless steel → lower yield but higher ductility
• Alloy steel → higher temperature strength
• Duplex → high yield and corrosion resistance

Design must ensure:

• operating stress < allowable stress
• adequate safety factor (typically 2–4 depending on service)

F. Mechanical Property Table

Material	Yield Strength (MPa)	Tensile Strength (MPa)	Elongation (%)	Hardness (HB)	Impact Value
ASTM A105	250	485	22	120–187	Moderate
ASTM A350 LF2	250	485	22	120–187	High (low temp)
ASTM A182 F304	205	515	30	≤ 201	High
ASTM A182 F316	205	515	30	≤ 217	High
ASTM A182 F22	415	585	20	170–220	Moderate

G. Corrosion Resistance Comparison Table

Material	Marine	Chemical	High Humidity	Hydrocarbon
Carbon Steel	Low	Low	Low	Moderate
SS304	Moderate	Moderate	High	High
SS316	High	High	High	High
Alloy Steel	Low	Moderate	Low	High
Duplex SS	Very High	Very High	Very High	High

8. Inspection & Quality Control Methods

Quality assurance for Threaded Flanges is essential to ensure pressure integrity and compliance with EPC specifications.

Thread Gauge Inspection

• Go gauge → verifies minimum engagement
• No-Go gauge → prevents oversize threads

Ensures compatibility with pipe threads.

PMI Testing (Positive Material Identification)

• Verifies alloy composition
• Conducted using XRF analyzers

Required for stainless steel and alloy grades.

Non-Destructive Testing (NDT)

Ultrasonic Testing (UT)

• detects internal discontinuities

Magnetic Particle Inspection (MPI)

• detects surface cracks (ferromagnetic materials)

Dye Penetrant Inspection (DPI)

• detects surface defects (non-magnetic materials)

Dimensional Inspection

Verification of:

• flange OD
• thickness
• bolt circle
• thread dimensions

Performed using calibrated instruments.

Hardness Testing

Ensures compliance with:

• ASTM limits
• project specifications

Prevents brittle failure.

Certification

EN 10204 3.1

• manufacturer test certificate

EN 10204 3.2

• third-party verified certificate

Third-Party Inspection Readiness

Inspection agencies may include:

• client-appointed inspectors
• independent certification bodies

Inspection scope includes:

• raw material verification
• in-process inspection
• final dimensional and NDT checks
• documentation audit

9. Industries Served

Threaded Flanges are deployed across multiple industrial sectors where non-welded piping connections are required under controlled pressure and temperature conditions. Their applicability is determined by system design philosophy, safety constraints, and maintenance accessibility.

Oil & Gas (Upstream / Midstream / Downstream)

Applications include:

• wellhead auxiliary lines
• chemical injection systems
• fuel gas distribution
• instrument air headers
• drain and vent piping
• tank farm utilities

Engineering considerations:

• preference in low-pressure hydrocarbon service
• avoidance in high-vibration rotating equipment discharge
• selection based on hazard classification (hot work restrictions)

Refineries

Used in:

• sampling lines
• analyzer connections
• bypass loops
• low-pressure process lines
• steam tracing auxiliaries

Threaded connections are selected where:

• shutdown durations are limited
• field welding is impractical
• temporary or modular piping is required

Power Plants

Applications include:

• service water systems
• compressed air lines
• lubrication oil piping
• auxiliary fuel systems

Limitations:

• not recommended for main steam lines
• restricted use in high-temperature cyclic service

Water Systems & Utilities

Widely used in:

• potable water distribution
• cooling water circuits
• compressed air networks
• HVAC piping systems

Advantages:

• ease of installation
• simplified maintenance
• reduced fabrication requirements

Fire Protection Systems

Common in:

• sprinkler networks
• hydrant systems
• jockey pump connections
• fire water ring mains

These systems operate within pressure ranges compatible with threaded joints and require quick installation and inspection.

Chemical & Process Plants

Applications include:

• low-pressure chemical transfer
• solvent handling lines
• dosing systems
• utility piping

Material selection (SS316 / Duplex) becomes critical for corrosion resistance.

General Utility & Infrastructure Piping

Includes:

• compressed gas systems
• municipal installations
• industrial utility corridors

Threaded flanges are preferred where:

• system flexibility is required
• future modifications are anticipated

10. Export Capability & Global Supply

Super Industries supplies Threaded Flanges for international EPC projects with compliance to multi-region standards and documentation requirements.

Export Regions

Supply coverage includes:

• United States (ASME-compliant systems)
• Europe (EN / DIN compliance)
• Middle East (project-specific EPC standards)
• Southeast Asia (mixed ASME / BS requirements)

Packaging Standards

Packaging is executed to maintain dimensional integrity and prevent thread damage:

• individual thread protection caps
• rust preventive application
• wooden crates / fumigated pallets
• moisture barrier wrapping
• export-grade strapping

Thread protection is mandatory to preserve tolerance accuracy during transit.

Export Documentation

Supplied documentation includes:

• commercial invoice
• packing list
• mill test certificates (EN 10204 3.1 / 3.2)
• inspection reports
• material traceability records
• country of origin certificate

Additional project-specific documentation may include:

• NDT reports
• heat treatment charts
• PMI reports

Project Logistics

Execution aligned with EPC schedules:

• lot-wise production tracking
• dispatch planning as per site priority
• container optimization
• coordination with freight forwarders

Critical considerations:

• preservation of machined threads
• prevention of corrosion during transit
• compliance with international shipping standards

Compliance Documentation

Each batch is aligned with:

• applicable ASME / ASTM standards
• project technical specifications
• inspection test plans (ITP)
• quality assurance plans (QAP)

Traceability is maintained from raw material heat number to final dispatch.

11. Procurement & Installation View

The performance of Threaded Flanges depends significantly on correct procurement specifications and installation practices.

Thread Sealing Methods

Sealing is achieved using:

• PTFE tape (standard applications)
• anaerobic thread sealants
• liquid thread compounds

Selection depends on:

• fluid type
• temperature
• pressure
• chemical compatibility

Installation Procedure

1. Inspect threads for damage or contamination
2. Clean mating threads thoroughly
3. Apply sealant uniformly
4. Engage threads manually to avoid cross-threading
5. Tighten using controlled torque
6. Align flange faces before bolting

Tightening Practices

• avoid excessive torque to prevent thread deformation
• ensure full engagement length
• maintain alignment to avoid bending stress

Improper tightening can result in:

• leakage
• thread stripping
• flange distortion

Alignment Precautions

• flange faces must be parallel
• piping misalignment must be corrected before assembly
• no forced alignment using bolts

Misalignment introduces:

• bending stresses
• uneven gasket compression
• premature failure

Field Inspection

Inspection prior to commissioning includes:

• verification of thread engagement
• sealant application check
• leak testing (hydro / pneumatic)
• bolt torque verification

Storage & Handling

Proper storage is required to maintain thread integrity:

• use protective caps on threads
• store in dry, covered environment
• avoid direct ground contact
• apply corrosion inhibitors if required

Damage to threads can compromise sealing performance.

12. Custom Engineering Capabilities

Super Industries manufactures Threaded Flanges in accordance with project-specific engineering requirements beyond standard catalog dimensions.

Non-Standard Thread Forms

Capability includes:

• BSPT / BSPP threads
• special pitch configurations
• project-specific thread tolerances

Special Pressure Ratings

Manufacturing can be adapted for:

• non-standard pressure classes
• reinforced hub designs
• higher safety factor requirements

Custom Dimensions

Production flexibility for:

• non-standard OD and thickness
• special drilling patterns
• compact flange configurations

Special Surface Coatings

Available options include:

• PTFE coating for chemical resistance
• hot-dip galvanizing for outdoor service
• anti-galling coatings for stainless steel

Project-Specific Marking

Marking can include:

• client identification codes
• project numbers
• heat traceability
• inspection stamps

Ensures compliance with EPC documentation requirements.

Engineering Conclusion

Threaded Flanges provide a mechanically reliable solution for non-welded piping connections within defined pressure, temperature, and service limits.

Their correct application depends on:

• understanding of thread sealing mechanics
• adherence to ASME and ASTM standards
• proper material selection
• controlled manufacturing and inspection
• disciplined installation practices

From an engineering perspective:

• they are suitable for low-to-medium pressure systems
• they simplify installation in restricted environments
• they enable maintenance-friendly configurations
• they require careful evaluation under vibration and thermal cycling

When designed, manufactured, and installed in accordance with applicable standards, Threaded Flanges meet the functional requirements of industrial piping systems used in oil & gas, power, petrochemical, and utility sectors.