Brass Fitting
Technical Specifications
A comprehensive reference guide covering thread standards, pressure ratings, material grades, and selection criteria -- engineered to help procurement managers and engineers specify the right fitting, first time.
Thread Standards
NPT, BSP & Metric Thread Guide
Selecting the correct thread standard is critical for leak-free performance. Mismatched threads are the leading cause of fitting failures. Use this reference to identify and verify thread types before ordering.
NPT
National Pipe Taper (USA/Canada)
- Standard
- ANSI/ASME B1.20.1
- Taper Angle
- 1° 47' (1/16 in/in)
- Seal Method
- Thread interference + PTFE tape
- Common Sizes
- 1/8" to 4"
- Primary Markets
- North America, Latin America
Key Note: NPT threads seal via taper interference. Always use PTFE tape or thread sealant. Do not use with BSP fittings -- thread pitch and angle differ.
BSP
British Standard Pipe (EU/Asia)
- Standard
- ISO 228 (BSPP) / ISO 7 (BSPT)
- Variants
- BSPP (parallel) / BSPT (taper)
- Seal Method
- BSPP: O-ring / BSPT: PTFE tape
- Common Sizes
- 1/8" to 6" (BSP nominal)
- Primary Markets
- Europe, Middle East, Asia-Pacific
Key Note: BSPP uses parallel threads; sealing relies on a bonded washer or O-ring at the face. BSPT uses a 1:16 taper similar to NPT but with different pitch -- not interchangeable.
Metric
ISO Metric Thread (Global)
- Standard
- ISO 261 / DIN 13
- Designation
- M + diameter × pitch (e.g. M12×1.5)
- Seal Method
- O-ring or copper washer
- Common Sizes
- M6 to M64
- Primary Markets
- Europe, China, Global OEM
Key Note: Metric threads are identified by outer diameter and pitch in millimeters. Fine pitch variants (e.g. M14×1.0) are common in hydraulic applications for higher pressure ratings.
Thread Standard Quick-Reference Comparison
| Parameter | NPT | BSPP (G) | BSPT (R) | Metric (M) |
|---|---|---|---|---|
| Thread Form | 60° taper | 55° parallel | 55° taper | 60° parallel |
| Pitch System | TPI (threads/inch) | TPI | TPI | mm pitch |
| Sealing | Thread taper | Face seal / O-ring | Thread taper | O-ring / washer |
| Interchangeable? | No | No | No | No |
| Governing Body | ANSI/ASME | ISO/BSI | ISO/BSI | ISO/DIN |
| Best Application | DOT brake, gas, air | Hydraulics, instrumentation | Fluid power, EU plumbing | Automotive, machinery |
Pressure Ratings
Working Pressure & Safety Reference
Pressure ratings depend on fitting type, size, wall thickness, and operating temperature. All Yaochong brass fittings are pressure-tested at 500 psi minimum. DOT-certified products comply with FMVSS 106 brake system specifications.
DOT Brake Fittings
3,000 psi
Burst test rating
Working pressure: 1,500 psi. FMVSS 106 compliant. For air brake and hydraulic brake lines.
NPT Standard Fittings
1,500 psi
Max working pressure
Varies by size. Larger sizes (≥ 1") typically rated lower. Suitable for air, water, and gas applications.
BSP Hydraulic Fittings
5,000 psi
Heavy-duty rated
High-pressure BSP fittings for hydraulic systems. O-ring face seal (ORFS) variants available for critical applications.
General Purpose
500 psi
Minimum test pressure
All Yaochong fittings are pressure-tested at 500 psi minimum. Standard for water supply, HVAC, and pneumatic systems.
NPT Brass Fitting -- Max Working Pressure by Size (psi @ 70°F)
| Nominal Size | Straight / Adapter | Elbow (90°) | Tee | Reducer | Plug / Cap |
|---|---|---|---|---|---|
| 1/8" (DN6) | 2,500 | 2,200 | 2,000 | 2,200 | 2,500 |
| 1/4" (DN8) | 2,000 | 1,800 | 1,600 | 1,800 | 2,000 |
| 3/8" (DN10) | 1,800 | 1,500 | 1,400 | 1,500 | 1,800 |
| 1/2" (DN15) | 1,500 | 1,200 | 1,100 | 1,200 | 1,500 |
| 3/4" (DN20) | 1,200 | 1,000 | 900 | 1,000 | 1,200 |
| 1" (DN25) | 1,000 | 850 | 750 | 850 | 1,000 |
Temperature Derating -- Important
Brass fittings maintain full rated pressure up to 150°F (65°C). Above this temperature, apply derating factors: 150-250°F: 75% of rated pressure · 250-350°F: 50% of rated pressure. For steam or high-temperature applications, consult our engineering team for appropriate material and fitting selection.
Always apply a safety factor of at least 4:1 (burst pressure to working pressure) for critical systems.
Material Comparison
Brass Alloy Grades & Material Properties
Yaochong uses premium H59 and H62 brass alloys -- the industry benchmark for fluid connection fittings. Understanding the differences helps you specify the right grade for your application environment.
H62 Brass
Cu 60.5-63.5% · Zn Balance · Standard Grade
Tensile Strength
380-440 MPa
Hardness
70-90 HB
Machinability
Excellent
Corrosion Resistance
Very Good
Key Properties
- Higher copper content -- superior corrosion resistance in water and air
- Excellent thread forming -- precise CNC machining for tight tolerances
- Widely accepted for DOT, plumbing, gas, and pneumatic applications
- Good ductility -- resists cracking under vibration and thermal cycling
Best For
DOT brake fittings, NPT adapters, water supply, HVAC, pneumatic systems, general industrial applications.
H59 Brass
Cu 57-60% · Zn Balance · Economy Grade
Tensile Strength
350-400 MPa
Hardness
60-80 HB
Machinability
Good
Corrosion Resistance
Good
Key Properties
- Cost-effective -- lower copper content reduces raw material cost
- Higher zinc content -- slightly harder, good for structural fittings
- Suitable for non-critical fluid applications and dry environments
- Widely available -- faster lead times for high-volume orders
Best For
Hardware wholesalers, general plumbing, non-corrosive environments, cost-sensitive large-volume procurement.
Brass vs. Alternative Fitting Materials
| Property | Brass (H62) | Stainless Steel | Carbon Steel | Plastic (Nylon) |
|---|---|---|---|---|
| Corrosion Resistance | Excellent | Excellent | Poor | Very Good |
| Machinability | Excellent | Moderate | Good | Moderate |
| Pressure Rating | High | Very High | High | Low |
| Cost (Relative) | Medium | High | Low | Low |
| DOT Approved | Yes | Yes | Limited | No |
| Temperature Range | -40°F to 350°F | -100°F to 800°F | -20°F to 500°F | -40°F to 200°F |
| Typical Applications | DOT brake, plumbing, pneumatics, gas | Chemical, food, marine | Hydraulics (with coating) | Low-pressure air/water |
Selection Guide
How to Select the Right Brass Fitting
Follow this structured decision process to specify the correct fitting for your application. When in doubt, our technical team is available to review your requirements and provide recommendations.
1 Identify the Thread Standard Required
Match the thread type to your system's existing connections or regional standard:
- North America (USA/Canada): Default to NPT. DOT brake systems require DOT-certified NPT fittings per FMVSS 106.
- Europe / Middle East / Asia-Pacific: Use BSP (BSPP for parallel, BSPT for taper). Verify with your end customer.
- OEM / Machinery: Metric threads are common. Check engineering drawings for M-designation and pitch.
- Identification Tip: Use a thread gauge or pitch gauge to measure TPI or mm pitch. Never assume thread type from visual inspection alone.
2 Determine Nominal Size & Port Size
Nominal pipe size (NPS) does not equal actual thread diameter -- it's a legacy designation. Use this reference:
| Nominal Size | OD (inch) | TPI (NPT) | TPI (BSP) |
|---|---|---|---|
| 1/8" | 0.405" | 27 | 28 |
| 1/4" | 0.540" | 18 | 19 |
| 3/8" | 0.675" | 18 | 19 |
| 1/2" | 0.840" | 14 | 14 |
| 3/4" | 1.050" | 14 | 14 |
| 1" | 1.315" | 11.5 | 11 |
3 Confirm Pressure & Temperature Requirements
State the maximum working pressure and operating temperature range for your system:
- Air/Pneumatic Systems: Typically 150-250 psi. Standard brass fittings are suitable.
- DOT Brake Systems: Must withstand 1,500 psi working / 3,000 psi burst. Only use DOT-certified fittings.
- Hydraulic Systems: 1,500-5,000 psi. Specify fitting type and consult our team for wall thickness confirmation.
- High-Temperature: Above 150°F requires derating. Above 350°F, consider stainless steel instead.
4 Select Fitting Type & Configuration
Choose the fitting geometry based on your piping layout:
Straight Connector
Inline connection of same or different size ports. Male-to-male, male-to-female, or union styles.
Elbow (45° / 90°)
Direction change. 90° most common; 45° for gradual bends. Street elbows have one male end.
Tee / Cross
Branch connections. Equal tees for same size; reducing tees for different branch sizes.
Reducer / Bushing
Size transitions. Hex bushings thread inside larger ports; reducers are inline.
Plug / Cap
Port closure. Plugs thread into female ports; caps thread over male ports.
Adapter
Thread standard conversion (e.g. NPT male to BSP female). Specify both thread types.
5 Specify Surface Treatment & Certifications
Select appropriate surface treatment for your environment and compliance requirements:
- Natural Brass (Bare): Standard. Good for indoor, dry, or oil-lubricated environments.
- Nickel Plating: Enhanced corrosion resistance, improved appearance. Common for automotive and pneumatic fittings.
- Chrome Plating: Decorative finish with good corrosion protection. Used in visible plumbing applications.
- DOT Certification: Required for U.S. brake system applications. Confirm FMVSS 106 compliance when ordering.
- Custom Packaging / OEM Marking: Available for brand owners and distributors. Discuss with our sales team.
Application Quick Selector
DOT Air Brake Systems
Thread
NPT
Material
H62 Brass
Certification
DOT / FMVSS 106
Max Pressure
1,500 psi WP
Industrial Pneumatics
Thread
NPT or BSP
Material
H59 or H62
Certification
ISO 9001
Max Pressure
250 psi typical
Hydraulic Systems
Thread
BSP or Metric
Material
H62 Brass
Seal
O-ring face seal
Max Pressure
Up to 5,000 psi
Hardware / Plumbing Wholesale
Thread
NPT or BSP
Material
H59 (cost-optimized)
MOQ
Flexible
Lead Time
Stock available
Common Specification Mistakes to Avoid
Mixing NPT and BSP
NPT and BSP have different thread angles (60° vs 55°) and pitch. They may appear to thread together but will leak under pressure. Always verify with a gauge.
Over-tightening Fittings
Brass is ductile but not indestructible. Over-torquing causes thread stripping or cracking. Follow manufacturer torque specifications and use 2-3 wraps of PTFE tape.
Ignoring Derating at Temperature
Pressure ratings are specified at 70°F. High-temperature applications require derating. Failure to derate is a leading cause of premature fitting failure.
Using Non-DOT Fittings in Brake Lines
U.S. regulations require DOT-certified fittings in brake systems. Non-certified fittings may fail compliance inspection and create liability exposure.
Assuming NPS = Thread OD
Nominal pipe size is a legacy designation -- a 1/2" NPT fitting has a 0.840" OD, not 0.5". Always cross-reference with actual thread dimensions.
No Safety Factor Applied
Always apply a minimum 4:1 safety factor (burst to working pressure) for critical systems. Pressure spikes and water hammer can briefly exceed rated working pressure.
Not Sure Which Fitting
Is Right for Your Application?
Our engineering team reviews your specifications, drawings, or samples and provides precise product recommendations -- at no cost. Serving wholesalers and procurement managers across North America, Europe, and beyond.
Megan (Sales)
megan@roadspower.com
WhatsApp: +86 135 8688 8913
Jack (Sales)
jack@roadspower.com
WhatsApp: +86 187 6807 9476
Certifications
ISO 9001 · DOT FMVSS 106
Ningbo, Zhejiang -- 30km from Port