Aluminum Pipe Cap

An aluminum pipe cap closes the end of an aluminum piping system. It is the smallest fitting in the line and the one that seals the system. That is exactly why the details matter: get the alloy, thread, or wall schedule wrong and the whole line is compromised.

 

GNEE supplies aluminum pipe caps in five alloys, three connection types, and two standard wall schedules from stock. For project orders we machine custom caps to your drawing, with full material traceability on every batch.

 

For standard butt-welding applications, ASTM B361 is used as the aluminum and aluminum-alloy welding fitting specification, while ASME B16.9 provides the dimensional framework for factory-made wrought butt-welding fittings. Where required, butt-welding end preparation can be specified to ASME B16.25. ASTM B361 specifically covers factory-made wrought aluminum and aluminum-alloy welding fittings and states that applicable fittings are made to dimensional standards such as ASME B16.9.

 

GNEE supports standard and custom aluminum pipe caps with multiple alloy options, sizes, wall thicknesses, and manufacturing configurations.

Larger diameters (up to DN600) and non-standard wall thicknesses are available as custom orders. Send us the drawing or spec sheet and we'll quote within 24 hours.

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Specification of GNEE Aluminum Pipe Cap

 

Parameter	Specification
Product Type	Aluminum Pipe Cap / Aluminum Pipe End Cap
Aluminum Alloy	6061, 6063, 6082, 5083, 5086, 1050, 1060, 1100, 3003, etc.
Temper	O, H32, H111, T5, T6, T651, etc., depending on alloy and product form
Nominal Pipe Size	NPS 1/2–24 (DN15–DN600); larger sizes available on request
Outer Diameter	According to nominal pipe size and applicable standard; custom dimensions available
Wall Thickness	According to mating pipe, applicable specification or customer drawing; custom wall thickness available
Type	Butt Weld, Seamless, Welded/Fabricated; Threaded, Socket-Weld and other configurations available where applicable
Thread	NPT, BSPT, BSPP, Metric; available for applicable threaded designs
Manufacturing Method	Formed, Forged, Machined, Welded/Fabricated, depending on alloy, size and design
Surface Finish	Mill Finish, Anodized, Polished, Sandblasted, Powder Coated
Material Standard	ASTM B361, where applicable
Dimensional Standard	ASME B16.9, where applicable
Welding-End Preparation	ASME B16.25, where specified
Additional Standard	MSS SP-43, where applicable
Inspection	Chemical Composition / PMI, Dimensional Inspection, Visual Inspection, Mechanical Testing and other agreed tests
Pressure Testing	Hydrostatic or other pressure testing available on request, subject to project requirements
Customization	Custom alloy, temper, size, wall thickness, end preparation and dimensions according to customer drawings

 

 

GNEE Aluminum Pipe Cap Alloy Grades

 

The aluminum alloy selected for a pipe cap directly affects its strength, corrosion resistance, weldability, formability, and suitability for different service environments. GNEE supplies aluminum pipe caps in a range of commonly used alloys for industrial, marine, structural, and custom applications.

 

Alloy	Typical Characteristics	Typical Use Considerations
1050	Commercially pure aluminum with high corrosion resistance, thermal conductivity, and excellent formability	General fabrication, heat-transfer components, and low-strength applications
1060	High-purity aluminum with excellent electrical and thermal conductivity and good corrosion resistance	General-purpose components, heat-transfer applications, and low-strength fabrication
1100	Commercially pure aluminum with good formability, corrosion resistance, and weldability	General industrial fabrication and equipment
3003	Al-Mn alloy with good formability, corrosion resistance, and moderate strength	General fabrication, HVAC, and selected piping applications
5083	Al-Mg alloy with high strength, excellent corrosion resistance, and good weldability	Marine piping, shipbuilding, and corrosion-resistant fabrication
5086	Al-Mg alloy with good corrosion resistance, weldability, and moderate-to-high strength	Marine and industrial fabrication
5154	Al-Mg alloy with good corrosion resistance and weldability	General engineering and fabricated components
6061	Heat-treatable Al-Mg-Si alloy with a good balance of strength, machinability, and corrosion resistance	Industrial components, structural applications, and selected piping systems
6063	Heat-treatable Al-Mg-Si alloy with excellent extrusion characteristics and good corrosion resistance	Extruded tubes, profiles, and general engineering components
6082	Heat-treatable Al-Mg-Si-Mn alloy with relatively high strength and good machinability	Structural components, transportation equipment, and custom engineered fittings

Material Note: Alloy availability depends on the required fitting form, temper, size, and applicable specification. GNEE confirms the final material designation before production rather than automatically treating every aluminum alloy as ASTM B361-compliant.

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6061-T6 Aluminum Pipe Cap

 

6061-T6 is a widely used heat-treatable aluminum alloy for engineering components where a combination of strength, machinability, corrosion resistance, and weldability is required.

Property	Typical Characteristic
Alloy	6061
Temper	T6
Alloy Type	Heat-treatable Al-Mg-Si alloy
Strength	High for a general-purpose aluminum alloy
Formability	Moderate in T6 condition

Typical Applications

General industrial piping

Equipment fabrication

Structural assemblies

Hydraulic and pneumatic equipment

General engineering components

 

5083-O Aluminum Pipe Cap

5083-O is a non-heat-treatable Al-Mg alloy known for its high strength, excellent corrosion resistance, and good weldability. It is widely used in marine and corrosion-resistant aluminum fabrication.

Property	Typical Characteristic
Alloy	5083
Temper	O
Alloy Type	Non-heat-treatable Al-Mg alloy
Formability	Good in O temper

Typical Applications

Marine piping

Shipbuilding

Marine equipment

Offshore fabrication

Corrosion-resistant structures

Selected cryogenic applications

5083 is commonly considered for marine and seawater-related applications where high corrosion resistance and good weldability are required.

 

6082 Aluminum Pipe Cap

6082 is a heat-treatable Al-Mg-Si-Mn alloy with relatively high strength and good machinability. It is commonly used for structural and engineering components.

Property	Typical Characteristic
Alloy	6082
Typical Temper	T6
Alloy Type	Heat-treatable Al-Mg-Si-Mn alloy
Strength	High
Formability	Moderate

Typical Applications

Structural frameworks

Transportation equipment

Marine structures

Industrial equipment

Machined components

Custom engineered fittings

 

1050 / 1060 Aluminum Pipe Cap

1050 and 1060 are commercially pure aluminum grades with relatively low strength but excellent corrosion resistance, thermal conductivity, and formability.

Typical Applications

Heat-transfer equipment

General fabrication

Chemical equipment

HVAC components

Low-strength piping or fabricated components

Applications requiring high aluminum purity

These alloys are selected where corrosion resistance, conductivity, or formability is more important than high mechanical strength.

 

How to Choose an Aluminum Pipe Cap Alloy

 

Application Requirement	Aluminum Alloys to Consider
General industrial use	6061, 6063, 3003
Higher structural strength	6061, 6082
Marine applications	5083, 5086
Corrosion-resistant fabrication	5083, 5086
High formability	1050, 1060, 1100, 3003
Heat-transfer applications	1050, 1060, 1100, 3003
Extruded tube or profile components	6063
Machined engineering components	6061, 6082

 

 

 

Dimension Reference - Standard Sizes

 

The table below provides a reference for common butt-weld aluminum pipe cap sizes. All dimensions are in mm unless otherwise specified.

Nominal Size	NPS	Outside Diameter (OD)	Wall Thickness - SCH 40	Wall Thickness - SCH 80	Reference Height
DN15	½″	21.3	2.77	3.73	25
DN20	¾″	26.7	2.87	3.91	25
DN25	1″	33.4	3.38	4.55	38
DN32	1¼″	42.2	3.56	4.85	38
DN40	1½″	48.3	3.68	5.08	38
DN50	2″	60.3	3.91	5.54	38
DN65	2½″	73.0	5.16	7.01	38
DN80	3″	88.9	5.49	7.62	51
DN100	4″	114.3	6.02	8.56	64
DN125	5″	141.3	6.55	9.53	76
DN150	6″	168.3	7.11	10.97	89
DN200	8″	219.1	8.18	12.70	102
DN250	10″	273.0	On Request	On Request	Custom
DN300	12″	323.9	On Request	On Request	Custom

 

Dimension Note: The OD values above correspond to common ASME B36.10 pipe outside diameters, while ASME B16.9 cap dimensions should be checked against the applicable fitting size and dimensional requirements. SCH 40 and SCH 80 wall thicknesses refer to the mating pipe and should not automatically be treated as the actual wall thickness of the formed pipe cap.

 

Customization: GNEE can supply custom outside diameters, wall thicknesses, heights, end preparations and other dimensions according to customer drawings or project specifications.

 

Standards for Aluminum Pipe Caps

 

GNEE aluminum pipe caps can be manufactured according to the applicable material, dimensional, manufacturing, and connection standards. The appropriate standard depends on the pipe cap type, manufacturing method, connection method, size, and project requirements.

Standard	Scope / Use
ASTM B361	Specification for factory-made wrought aluminum and aluminum-alloy welding fittings. It covers applicable butt-welding and socket-end fittings and references dimensional standards such as ASME B16.9 and ASME B16.11.
ASME B16.9	Covers dimensions, tolerances, ratings, testing, marking, and other requirements for applicable factory-made wrought butt-welding fittings. It is the primary dimensional standard to consider for butt-weld aluminum pipe caps when specified.
ASME B16.52	Covers forged nonferrous fittings made from titanium, titanium alloys, aluminum, and aluminum alloys with socket-welding or threaded ends. It is applicable to forged aluminum fittings of the covered types, rather than general butt-weld caps.
MSS SP-43	Covers wrought and fabricated butt-welding fittings for low-pressure, corrosion-resistant applications. The current MSS SP-43-2026 edition covers fittings for Schedule 5S or 10S pipe, with short-pattern stub ends for Schedule 40S also included.
ASME B16.25	Covers butt-welding end preparation, including the dimensions and preparation of welding ends where this standard is specified for the connection.

Standard Selection Note

The applicable standard depends on the pipe cap type, material, manufacturing process, connection method, dimensions, and intended service.

 

Dimensional Tolerances

 

For products specified to ASME B16.9, the applicable dimensions and tolerances are controlled by the standard.

ASME B16.9 covers overall dimensions and tolerances for factory-made wrought butt-welding fittings.

 

For custom aluminum pipe caps, GNEE can additionally control customer-defined dimensions such as:

Inspection Dimension	Control Basis
Outside Diameter	Applicable standard or approved drawing
Inside Diameter	Applicable standard or approved drawing
Wall Thickness	Material/fitting specification or drawing
Overall Height	Applicable fitting standard or drawing
Welding-End Diameter	Applicable standard or drawing
Bevel / End Preparation	ASME B16.25 where specified
Roundness	Applicable product specification or drawing
Surface Condition	Customer specification
Weld Profile	Approved welding procedure / project specification

 

Welding End Preparation

 

For butt-weld aluminum pipe caps, the welding end must match the mating pipe and the welding procedure.

ASME B16.25 covers preparation of butt-welding ends, including welding bevels and related dimensions and tolerances.

Depending on the design, the purchase specification may include:

• Plain end
• Beveled end
• Single-V preparation
• Custom welding-end preparation
• Drawing-controlled end preparation

 

GNEE can manufacture the end preparation according to the applicable standard or customer-approved drawing.

 

The exact bevel angle, land/root face and other welding-end dimensions should not be stated as universal values without reference to the applicable edition of the standard and fitting configuration.

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Quality Inspection

 

• PMI (Positive Material Identification) to verify alloy composition
• Dimensional inspection - OD within ±0.5%
• Visual inspection for surface defects
• Thread gauging on threaded caps (NPT / BSPT)
• Hydrostatic testing available on request (adds 3–5 days to lead time)

 

Certifications

• EN 10204 3.1 material certificates (standard with every order)
• Mill Test Reports showing chemical composition and mechanical properties
• 3.2 certificates with third-party inspection available (TÜV, SGS, BV - specify when ordering)
• Certificate of Origin included for customs clearance

 

Packaging & Shipping

 

Each cap is individually wrapped in VCI (volatile corrosion inhibitor) film or a plastic bag, then packed in cartons or fumigated wooden crates - ISPM 15 compliant. Labels include purchase order number, alloy grade, size, quantity, and net/gross weight.

 

 

Shipping options:

 

- FOB Shanghai / Ningbo / Tianjin / Qingdao - specify preferred port
- CIF to your destination port - we arrange freight and insurance
- EXW from our factory - you handle pickup and logistics

 

Typical lead times:

 

Order Type	Lead Time
Stock sizes, standard alloys	7–15 days
Custom sizes or non-stock grades	20–30 days
Large quantity (5,000+ pieces)	25–40 days
Samples (stock items)	3–5 days

 

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