Metric Hydraulic Fittings are primarily used in hydraulic equipment, pipelines, and mechanical connection systems based on ISO metric threads. Compared to imperial or pipe thread systems like BSP, NPT, and JIC, their key identifiers are the M thread designation, tube diameter, and sealing structure.
HBFittings offers a comprehensive product range covering hydraulic fittings, reusable hose fittings, and tube fittings, all supporting Metric M threads. Their reusable hydraulic hose fittings are available in JIC, BSP, BSPT, and NPT connections, while certain tube fittings come in both Metric M and imperial sizes.
Therefore, when purchasing Metric Hydraulic Fittings, simply specifying "M12" or "M16" is insufficient. A complete inquiry should also include:
• Thread size
• Thread pitch
• Male / Female
• Tube OD or hose I.D.
• Sealing method
• Fitting type
• Material
• Pressure rating
1. What Are Metric Hydraulic Fittings?
Metric Hydraulic Fittings are hydraulic connectors based on the metric sizing system.
Common applications include:
• Hydraulic machinery
• Construction equipment
• Agricultural machinery
• Industrial automation
• Hydraulic power units
• Hydraulic pipelines
• Instrumentation systems
HBFittings offers hydraulic fitting products covering various connection standards, along with non-standard and OEM customization. The website explicitly states that customers can provide specific requirements via samples or drawings for custom manufacturing.
Common connection types for Metric fittings include:
Metric Threads (e.g.):
• M10
• M12
• M14
• M16
• M18
• M20
• M22
• M24
Metric Tube Connections (e.g.):
• 6 mm
• 8 mm
• 10 mm
• 12 mm
• 15 mm
• 16 mm
• 18 mm
• 20 mm
When making actual purchases, the thread size and tube outer diameter (OD) must be confirmed separately.
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2. Why Metric Hydraulic Fittings Need Careful Selection
The most common issue with Metric fittings is that similar-looking dimensions can actually represent different specifications.
For example:
• M16 × 1.5
• M16 × 2.0
While both have an outer diameter close to 16 mm, they feature different pitches and cannot be directly interchanged.
Similarly, the following cannot be swapped just because their sizes are comparable:
• M18
• G3/4
• 3/4 NPT
Therefore, when purchasing Metric Hydraulic Fittings, you must confirm at least the following parameters:
Thread diameter + Pitch + Connection type + Seal method
3. Metric Thread Identification
Metric threads are typically designated as:
M + nominal diameter
For example:
M16
However, a complete specification usually requires:
M16 × 1.5
Where:
• M = Metric thread
• 16 = Nominal thread diameter
• 1.5 = Thread pitch
Therefore:
M16
and:
M16 × 1.5
do not represent the same level of complete information.
4. Metric Thread Pitch
Thread pitch is a mandatory parameter to confirm when purchasing Metric fittings.
For example, an M16 thread can come in different pitches:
• M16 × 1.0 (1.0 mm pitch)
• M16 × 1.5 (1.5 mm pitch)
• M16 × 2.0 (2.0 mm pitch)
If the pitch does not match:
• The threads will not engage correctly;
• The sealing surfaces will not align properly;
• Forced installation may damage the threads.
Therefore, if the customer has not explicitly specified the thread pitch, it is best to request:
Drawing / Sample / Existing Part Number
5. Metric Hydraulic Fittings vs BSP
Metric and BSP are two completely different thread systems.
|
Item |
Metric |
BSP |
|
Thread system |
ISO Metric |
British Standard Pipe |
|
Typical marking |
M16 × 1.5 |
G1/2 / R1/2 |
|
Dimension |
mm |
Nominal inch |
|
Pitch |
mm |
TPI / standardized pitch |
|
Direct interchange |
No |
No |
HBFittings' reusable hydraulic hose fittings are available in multiple thread systems, including Metric, BSP, BSPT, and NPT. Therefore, buyers must explicitly specify the thread system rather than just providing a nominal size.
6. Metric Hydraulic Fittings vs NPT
Metric threads are typically straight threads, whereas NPT refers to tapered pipe threads.
HBFittings' recently published thread guide also categorizes M threads, NPT, and G threads separately. Specifically, M threads fall under ISO Metric straight threads, while NPT is classified as a tapered pipe thread.
Therefore:
M16 × 1.5 ≠ 1/2 NPT
As a general rule, Metric ports are common on machinery manufactured in Europe or Asia, while NPT is more prevalent in equipment using North American piping standards.
7. Metric Hydraulic Tube Fittings
Metric tube fittings and hydraulic hose fittings are not entirely the same.
They are primarily used for:
• Steel tubes
• Stainless steel tubes
• Instrument tubing
• Hydraulic tubing
HBFittings' compression tube fittings support metric tube sizes ranging from 2 mm to 50 mm, and are available in:
• SS304
• SS316
• Brass
• Special alloys
Depending on the specific design and specifications, these products can handle pressure ratings of up to 3,000–6,000 psi.
8. Metric Compression Fittings
Compression fittings are one of the most common configurations in Metric tube connections.
Typical structure:
Tube
↓
Back Ferrule
↓
Front Ferrule
↓
Fitting Body
↓
Compression Nut
HBFittings 对 double ferrule compression fitting 的资料显示,其结构包括：
• Compression nut
• Back ferrule
• Front ferrule
• Fitting body
It is available in a standard metric size range of 2–50 mm.
This design is suitable for:
• Hydraulic systems
• Instrumentation
• Chemical equipment
• Pneumatic systems
• Oil & gas
• Semiconductor equipment
9. Single Ferrule vs Double Ferrule Metric Fittings
When purchasing Metric tube fittings, it is necessary to further confirm whether a Single Ferrule or Double Ferrule design is required.
Single Ferrule
This design features a simpler structure and is suitable for:
• General tubing
• Moderate pressure applications
Double Ferrule
In this configuration, the front and back ferrules serve distinct functions:
• Front ferrule: Creates the seal.
• Back ferrule: Provides tube grip.
According to HBFittings' documentation, the double ferrule design forms a seal between the front ferrule, the tube's outer diameter, and the fitting body, while the back ferrule applies radial clamping force to the tube.
10. Metric Hydraulic Fitting Sealing Methods
Metric fittings are not limited to a single sealing method. Common types include:
O-Ring Seal
Ideal for locations requiring reliable static sealing.
Cone Seal
Forms a seal through conical surface contact.
Compression Seal
Creates a seal by compressing the ferrule against the tube.
Bonded Seal
Frequently used in certain threaded port connections.
Thread Seal
Some connections achieve sealing directly through the threads themselves.
Therefore:
Metric thread ≠ Sealing method
Both parameters must be confirmed simultaneously when making a purchase.
11. Metric Hydraulic Fitting Material Selection
HBFittings' reusable hydraulic hose fittings are available in materials including SS304, SS316, and SS316L.
For Metric Hydraulic Fittings, the appropriate material should be selected based on the operating environment:
Carbon Steel
Ideal for:
• Construction machinery
• General hydraulic equipment
• Industrial machinery
Key considerations:
• Surface treatment
• Corrosion protection
• Pressure rating
SS304
Suitable for:
• Outdoor equipment
• General corrosive environments
• Peripheral piping for food-related machinery
SS316 / SS316L
Designed for:
• Marine applications
• Offshore operations
• Chemical equipment
• High-humidity environments
HBFittings emphasizes the corrosion resistance of its SS304/316 reusable fittings and provides material certificates for these products.
12. Metric Hydraulic Fitting Pressure Rating
The metric thread itself does not determine the pressure rating of a fitting.
Pressure capacity is also influenced by:
• Material
• Wall thickness
• Fitting design
• Seal structure
• Tube size
• Hose construction
HBFittings' reusable hose fittings are designed for high-pressure hydraulic systems and support pressure certificates.
When purchasing, it is recommended to confirm both:
Working Pressure
and:
Maximum / Peak Pressure
Instead of simply asking:
"Is it high pressure?"
You should directly provide:
"System working pressure: XX bar / XX MPa"
13. Metric Hydraulic Fittings for SAE 100R2 Hose
If Metric fittings are used in hydraulic hose assemblies, the hose specifications must be considered simultaneously.
HBFittings' reusable hose fittings support SAE 100R2 / 2SN hoses and are available with various end connection standards, including Metric, JIC, BSP, BSPT, and NPT.
When purchasing, it is recommended to provide the following details:
• Hose standard
• Hose I.D. (Inner Diameter)
• Hose brand
• Working pressure
• Fitting thread
• Material
Example:
• SAE 100R2 hose
• 1/2" I.D.
• Metric M18 × 1.5 fitting
• SS316 material
14. Metric Hydraulic Fitting Size Selection
It is recommended to follow a three-step process for size selection:
Step 1 - Measure the Thread
Measure the following:
• Major diameter
• Thread pitch
Step 2 - Confirm the Tube or Hose Size
For example:
• Tube OD: 8 mm
• Tube OD: 10 mm
• Tube OD: 12 mm
Or:
• Hose I.D.: 1/4"
• Hose I.D.: 3/8"
• Hose I.D.: 1/2"
Step 3 - Confirm the Port
Verify the equipment connection interface:
• Male or Female
• Thread standard (Metric, BSP, NPT, JIC, etc.)
15. Metric Hydraulic Fittings for Construction Machinery
Construction machinery extensively utilizes metric sizing, making Metric fittings highly suitable for:
• Excavators
• Loaders
• Cranes
• Concrete equipment
• Agricultural machinery
Key factors to consider include:
Vibration
Equipment is subjected to continuous vibration during operation.
Pressure Pulsation
Hydraulic system pressure is not constant.
Hose Movement
Moving hydraulic hoses impose additional stress on fitting connections.
Outdoor Environment
Equipment is frequently exposed to harsh conditions, including:
• Rain
• Dust
• Mud
• Humidity
in the environment
16. Metric Hydraulic Fittings for Industrial Equipment
工业设备采购通常更关注：
• Dimensional accuracy
• Repeatability
• Pressure rating
• Material traceability
• Long-term sealing
• Replacement availability
HBFittings 的产品资料显示,其 hydraulic fitting production 涉及原材料化学分析,CNC machining,thread inspection,surface inspection 等环节;其 reusable fitting 产品还支持 material 和 inspection certificates.
对于批量采购,建议把：
Part Number + Drawing + Material + Thread
固定下来.
这样后续补货更容易控制.
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17. Metric Hydraulic Fittings for Marine Applications
6
Marine equipment 对 fitting 的要求与普通机械不同.
主要问题：
Corrosion
如果设备长期处于：
• Salt spray
• Sea water
• High humidity
环境中,建议优先考虑：
SS316 / SS316L
HBFittings 的 SS316/316L reusable fitting 产品就是针对需要 corrosion resistance 的液压连接场景.
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18. Metric Hydraulic Adapter
8
当设备一端是 Metric thread,而另一端是：
• BSP
• BSPT
• NPT
• JIC
就需要使用 adapter.
例如：
M18 × 1.5 → G1/2
或者：
M22 × 1.5 → 1/2 NPT
采购时必须明确两端：
End A
Metric M18 × 1.5 Male
↓
Adapter Body
↓
End B
BSPP G1/2 Female
HBFittings 的产品体系支持 Metric,BSP,BSPT,NPT 等连接标准,因此适合根据设备接口进行转换选型.
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19. Reusable Metric Hydraulic Fittings
4
对于维修市场,reusable fitting 有明显优势.
HBFittings 的 reusable hydraulic hose fittings：
• 可现场安装;
• 不需要 crimping machine;
• 可以拆卸;
• 可用于 hydraulic repair;
• 支持不同 thread standards;
• 可匹配 SAE100R2 / 2SN hose.
适合：
• Field service
• Hydraulic repair
• Replacement hose
• Remote machinery maintenance
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20. Metric Hydraulic Fittings Quality Inspection
6
批量采购时,建议检查：
Dimensional Inspection
确认：
• OD
• ID
• Length
• Thread diameter
Thread Inspection
确认：
• Thread pitch
• Thread gauge
• Thread depth
Sealing Surface
检查：
• Scratches
• Burrs
• Surface damage
Material
确认：
• Material grade
• Material certificate
Pressure
根据产品要求进行 pressure testing.
HBFittings 的生产资料显示,其 CNC 加工过程中会检查 ID,OD 和 thread,生产完成后还会进行 thread 和 surface inspection.
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21. Common Metric Hydraulic Fittings Buying Mistakes
6
Mistake 1 - Only Specify M Size
例如：
M16 fitting
信息不足.
应该明确：
M16 × 1.5 Male
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Mistake 2 - Confusing Metric and BSP
例如：
M20 ≠ G3/4
不要根据外径接近程度替换.
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Mistake 3 - Ignoring Sealing Method
相同 Metric thread：
可能对应不同：
• O-ring
• Cone
• Compression
• Bonded seal
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Mistake 4 - Choosing Fitting Without Hose Data
Hose 的：
• I.D.
• Construction
• Pressure rating
都会影响 fitting selection.
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Mistake 5 - Ignoring Material
室内普通设备和海洋设备的材料要求完全不同.
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22. Metric Hydraulic Fittings Buying Checklist
Item What to Confirm
Thread System Metric
Thread Diameter M10 / M12 / M16 / M20...
Pitch 1.0 / 1.5 / 2.0 mm...
Gender Male / Female
Tube OD mm
Hose I.D. inch / mm
Connection Thread / Compression / Flare
Seal O-ring / Cone / Ferrule
Shape Straight / Elbow / Tee
Material SS304 / SS316 / Steel / Brass
Pressure Working / Peak
Medium Oil / Water / Gas
Temperature Operating range
Application Machinery / Industrial / Marine
Certificate Material / Pressure / Inspection
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23. What to Send for a Metric Fittings Quote
4
如果向 HBFittings 询价,建议直接提供以下资料：
Product Type
例如：
Metric Male Hydraulic Fitting
Thread
M18 × 1.5
Connection
Male
Hose / Tube
12 mm Tube OD
Material
SS316
Seal
O-ring
Pressure
XXX bar
Application
Hydraulic Excavator
Quantity
XXX pcs
如果没有完整规格,可以发送：
• Existing fitting photo
• Sample
• Drawing
• Equipment model
• Port specification
HBFittings 网站明确支持根据 sample 或 drawing 制造非标准产品,并接受 OEM 定制.
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24. Metric Hydraulic Fittings Selection Process
6
实际采购可以按照下面的顺序进行：
Application
↓
Hydraulic Hose or Tube
↓
Metric Port Identification
↓
Thread Diameter
↓
Thread Pitch
↓
Male / Female
↓
Sealing Method
↓
Fitting Shape
↓
Material
↓
Pressure Rating
↓
Inspection & Certificate
↓
Final Metric Hydraulic Fitting
HBFittings 的产品和技术资料覆盖 Metric M,BSP,BSPT,NPT,JIC 等连接标准,并提供 reusable hose fittings,compression tube fittings 以及定制产品.
对于 Metric Hydraulic Fittings,真正需要采购双方确认的不是一个"M规格",而是一整套参数：
M Thread + Pitch + Connection + Seal + Tube/Hose Size + Material + Pressure
这也是后续批量采购,替换件匹配和 OEM 配套时最值得固定下来的产品信息.
