Direct Coupling

Product Overview

Sikerui PPH Direct Coupling is a high-performance pipe fitting engineered from high-molecular-weight homopolymer polypropylene (PPH), specifically modified with beta-crystallization technology to achieve a uniform microcrystalline structure that delivers exceptional chemical resistance and long-term performance. This critical component creates seamless, inline connections between two pipes of identical diameters, ensuring continuous flow in industrial piping systems while leveraging PPH’s renowned durability against corrosive agents and thermal stress. Manufactured to comply with international standards including DIN 8077/8078 and ISO 4422, it excels in demanding applications from chemical processing to water distribution systems. With a service life exceeding 50 years​ under rated conditions, PPH Direct Couplings combine lightweight simplicity with robust performance, offering a sustainable alternative to metal fittings while maintaining reliable operation in temperatures from -20°C to +110°C.

Features of PPH Direct Coupling

Exceptional Chemical Resistance

PPH material exhibits superior resistance to aggressive chemicals, withstanding pH values from 1-14 while maintaining structural integrity against high-concentration acids and alkalis. This makes it ideal for industrial effluent systems, chemical transport, and applications where metal fittings would rapidly corrode.

Thermal Stability and Pressure Retention

The beta-modified crystalline structure provides enhanced thermal performance, allowing continuous operation at temperatures up to 110°C while maintaining pressure ratings up to PN16 (1.6 MPa). This thermal stability prevents deformation under varying operational conditions, ensuring long-term sealing integrity.

Optimized Flow Characteristics

Featuring a smooth interior surface​ with consistent wall thickness, PPH Direct Couplings minimize turbulence and pressure drop while preventing scaling and sediment accumulation. The precision-molded interior maintains optimal flow efficiency in both water and viscous fluid transport applications.

Fusion Welding Compatibility

Designed for seamless thermal fusion joining, these couplings create permanent, leak-free connections that exceed pipe strength when properly welded. The material’s controlled thermal expansion characteristics ensure uniform fusion without sagging or obstruction, creating monolithic system integrity.

Durability and Environmental Resistance

PPH material offers exceptional abrasion resistance​ (4 times more wear-resistant than steel pipes) and maintains mechanical properties in outdoor applications, resisting UV degradation and environmental stress cracking. The homogeneous material structure ensures consistent performance throughout the product’s lifespan.

Material Advantages of PPH

Superior Crystalline Structure

PPH material undergoes specialized beta modification​ that creates a uniform microcrystalline structure, enhancing chemical resistance and pressure capability compared to standard polypropylene. This molecular arrangement provides improved stress distribution and crack propagation resistance.

Enhanced Mechanical Properties

The high molecular weight and controlled crystallinity deliver excellent tensile strength and stiffness​ while maintaining flexibility enough to withstand water hammer and pressure surges. The material’s creep resistance ensures dimensional stability under continuous load.

Material Purity and Safety

As a non-toxic, odorless material​ compliant with drinking water standards, PPH is suitable for potable water applications without affecting taste or water quality. The material’s inherent corrosion resistance eliminates leaching concerns associated with metal alternatives.

Typical Applications of PPH Direct Coupling

Chemical Processing Systems

In chemical plants and industrial facilities, PPH Direct Couplings provide reliable connections for aggressive media​ including acids, alkalis, and solvents where metallic fittings would quickly fail. The material’s chemical inertia ensures long-term system integrity in pharmaceutical production, chemical manufacturing, and electroplating applications.

High-Purity Fluid Handling

The non-contaminating properties​ of PPH make these couplings ideal for ultrapure water systems, pharmaceutical processing, and food and beverage applications where material compatibility and cleanliness are critical. The smooth interior surface prevents bacterial growth and biofilm formation.

Industrial Waste and Drainage Systems

PPH couplings offer superior corrosion resistance​ in aggressive waste streams, mining operations, and drainage applications where abrasive slurries and chemical-laden fluids would degrade alternative materials. The abrasion resistance ensures extended service life in slurry transport systems.

Technical Specifications

Table: PPH Direct Coupling Technical Data

Parameter​	Specification​	Standard/Note​
Material​	Beta-modified homopolymer polypropylene (PPH)	DIN 8077/8078
Temperature Range​	-20°C to +110°C (continuous)	Peak temperature 110°C
Pressure Rating​	PN10 to PN16 (1.0-1.6 MPa)	Size-dependent
Chemical Resistance​	pH 1-14, resistant to most acids, alkalis, and solvents	Except strong oxidizers
Service Life​	>50 years at rated conditions	Proper installation required
Standards Compliance​	DIN, ISO, ASTM	International certification

 

SIZE	Number	D1	D2	L1	L2
DN15	ZJ15	20.3	26.3	16.5	34.4
DN20	ZJ20	25.3	31.9	19	39
DN25	ZJ25	32.35	39.95	22.5	46.27
DN32	ZJ32	40.4	49.8	26.5	54.38
DN40	ZJ40	50.45	60.25	31.5	64.39
DN50	ZJ50	63.5	75.9	38	85.11
DN65	ZJ65	75.5	88.91	44	90.16
DN80	ZJ80	90.55	105.15	51.5	106.32
DN100	ZJ100	110.6	127.39	61.5	138.49
DN125	ZJ125	140.6	161.4	76	159.61
DN150	ZJ150	160.7	184.5	86.5	179.35
dn200	ZJ200	200	228.1	106.2	218
DN200	ZJ200	226.2	253.8	118.5	243.03
dn250	ZJ250	250	281.89	131.5	268
DN250	ZJ250	281.5	315.5	147	299
DN300	ZJ300	316.7	355	165	343
DN350	ZJ350	356.8	395	185	376
DN400	ZJ400	402	442	208	424
DN250 (PN10)	ZJ250	280.6	306	147	299
DN300 (PN10)	ZJ300	315.7	344	166	343
DN350 (PN10)	ZJ350	355.8	385	183.5	373
DN400 (PN10)	ZJ400	401	432	208	423

FAQs of Sikerui PPH Direct Coupling​

Q1: Can you customize Direct Couplings for non-standard lengths or diameters?​

Yes, we offer tailored solutions for dimensions (DN15–DN600), pressure ratings, and connection methods (e.g., threaded ends) to meet specific project needs.

Q2: How can I evaluate the product quality before placing a bulk order?​

Sample couplings are available for testing. Specifications are confirmed within 3–5 days, with samples shipped within one week after agreement.

Q3: What is the typical lead time for orders?​

Standard delivery takes 2–3 weeks after order confirmation. Urgent orders for common sizes (e.g., DN25–DN110) can be expedited.

Q4: How do you handle quality issues?​

Each coupling undergoes pressure and material checks per ISO 9001. Verified defects are covered by a warranty, with replacements or refunds processed promptly.

Q5: What payment terms do you accept?​

We support T/T, L/C, and options like 30% advance payment. Trade terms (EXW, FOB, CIF) are flexible for international clients.