Specialised Construction Fasteners: Primus India's Product Portfolio

Primus India (Primus Fasteners India) is a Pune-based supplier of industrial fasteners for roofing, cladding and pre-engineered building (PEB) work. Its range covers valley fixing, crest fixing, stitching and heavy-duty fasteners, along with a group of specialised products built around particular sheeting and panel materials. This article looks at that specialised group: the Pro Bonded Washer Series OD-19, fiber cement fasteners, PUF panel fasteners, polycarbonate sheet fasteners and wafer head fasteners. It also explains the technologies behind them, including PriSeal™ Ruspert Polymer Coating, the Trishul™ drill point and Deks sealing washers. Every specification below comes from the Primus India website.

What Are Specialised Construction Fasteners?

Specialised construction fasteners are screws engineered for a defined cladding, panel or substrate material rather than for general fixing. The differences show up in four places: the head or flange that spreads load, the drill point that cuts into the steel or timber support, the coating that protects the steel body, and the washer that seals the fixing point.

In the Indian construction industry, roofing and wall cladding on industrial and PEB structures use a wide mix of sheet materials, from metal and polycarbonate to insulated panels. Primus India organises its specialised range around these materials, so each product family carries its own combination of head, drill point and washer.

Primus India's Specialised Fastener Portfolio

Primus lists nine product families on its website. Four are core roofing and structural lines: valley fixing, crest fixing, stitching and heavy-duty fasteners. The other five are the specialised products covered here. The table summarises the stated product data.

Product	Stated purpose	Head	Drill point	Sealing washer
Pro Bonded Washer Series OD-19	Fixing metal to hot rolled steel, 1 mm to 6 mm	Hex washer head 8 mm, flange ø14.7	Trishul™ #3.5	Patta OD-19 bi-metal bonded washer
Fiber Cement Fasteners	Non-asbestos sheeting into metal and timber	Hex washer head 8 mm, flange ø14.7	Trishul™ #5, pilot-hole wing	EPDM dome washer OD-25
PUF Panel Fasteners	Insulated panel sheeting into metal	Hex washer head 8 mm, flange ø14.7	Trishul™ #5	OD 19 bi-metal bonded washer
Polycarbonate Sheet Fasteners	Polycarbonate sheet into metal and timber	Hex washer head 8 mm, flange ø14.7	Trishul™ #5, pilot-hole wing	DEKS EPDM dome washer (26 mm/32 mm), DEKS weather-lock washer
Wafer Head Fasteners	Clips to the secondary substrate	Wafer head	Trishul™ #5	Not listed

All five are made from case hardened carbon steel SAE 1022, heat treated to AS 3566.1, and carry PriSeal™ Ruspert Polymer Coating tested to ASTM B117 and DIN 50018.

Pro Bonded Washer Series OD-19

A bonded washer fastener is a self-drilling screw with a sealing washer permanently attached under the head. The washer fills the gap between the screw head and the sheet surface, so the fixing point is sealed by the fastener itself.

In this series the washer is the Patta OD-19 bi-metal bonded washer. Primus's OD-19 technical page describes a grey EPDM bonded washer with double gripping, built as a 1 mm metal base with 3 mm of EPDM. It is paired with an enlarged hex head flange, which Primus says gives superior load distribution. In Primus's range, "OD" is read as outside diameter: the technical pages pair OD-19 and OD-25 with washer descriptions, though the site does not spell this out.

The product page lists an 8 mm hex washer head, a ø14.7 mm flange and a Trishul™ #3.5 drill point. It also gives the series a 1 mm to 6 mm range for fixing metal to hot rolled steel. The same OD 19 bonded washer appears on the PUF panel fastener, so it works as a shared sealing component across the portfolio.

Fiber Cement Fasteners

Primus designs its fiber cement fasteners for fixing non-asbestos sheeting into metal and timber. The product has a hex washer head of 8 mm with a ø14.7 flange, and a Trishul™ #5 drill tip.

Two features set it apart within the range. The first is a pilot-hole special wing, which the page says gives better grip. The second is the EPDM dome washer OD-25, a larger sealing washer than the OD-19 used on the bonded series. The page lists a maximum steel thickness of 12 mm, PriSeal™ coating, and a body made from SAE 1022 steel to the AS 3566 Class 3 series.

PUF Panel Fasteners

PUF (polyurethane foam) panels are insulated sandwich panels, with metal skins around an insulating core. PUF panel fasteners are Primus's screws for fixing insulated panel sheeting into metal, and the site also files them under composite and panel fasteners.

The product combines the 8 mm hex washer head and ø14.7 flange with a Trishul™ #5 drill tip and an OD 19 bi-metal bonded washer. Using a bonded washer here means the sealing element is part of the screw assembly. The page lists a maximum steel thickness of 12 mm, PriSeal™ coating and SAE 1022 steel to the AS 3566 Class 3 series.

Polycarbonate Sheet Fasteners

Polycarbonate sheet fasteners, often called polycarbonate screws, are self-drilling screws for fixing polycarbonate sheet into metal and timber. The Primus polycarbonate range uses the same 8 mm hex washer head and ø14.7 flange as its sister products, with a Trishul™ #5 drill point and a pilot-hole special wing for better grip.

The washer is the most distinctive element. Primus pairs the screw with a DEKS engineered EPDM dome washer in 26 mm or 32 mm diameter, and also lists a DEKS engineered weather-lock washer. The sizes shown are fine-threaded #14G, 14 TPI, in 50 mm and 65 mm lengths. The body is SAE 1022 case hardened steel with PriSeal™ coating, and the page lists a maximum steel thickness of 12 mm.

Wafer Head Fasteners

A wafer head is a wide, low-profile screw head without a separate washer flange. Primus's wafer head fasteners are designed for fixing clips to the secondary substrate, and the page notes that these clips hold the roof.

The product carries a Trishul™ #5 drill point and PriSeal™ coating, and the page lists a maximum steel thickness of 12 mm. Listed sizes are fine-threaded: #10G, 24 TPI, 25 mm and #12G, 24 TPI, 32 mm. It is the only product in this group with no sealing washer, which reflects its role as a clip-fixing fastener rather than a sheet-fixing one.

Engineering Features Behind Primus Fasteners

The same few technologies recur across the specialised range. That consistency is what lets a polycarbonate screw and a PUF panel screw share a coating, a drill-point family and a quality system.

PriSeal™ Ruspert Polymer Coating

PriSeal™ Ruspert Polymer Coating is Primus's corrosion-protection finish. Primus describes it as a non-organic, tri-layered polymer coating with a grey finish. The first layer is metallic zinc, the second is an anti-corrosion chemical conversion film, and the third is a baked polymer top coat.

Primus designs it to conform to AS 3566 Class 3, which it classifies for general external use in mild and moderate industrial and mild marine environments. The site reports 1,000 hours of ASTM B117 salt spray with average red rust below 2% for Class 3 coatings, 7 cycles of the Kesternich test to DIN 50018, and a minimum coating thickness of 30 µm. Fasteners also carry a "PC" mark on the head.

Trishul™ Drill Point

The Trishul™ drill point is a patented design for self-drilling performance. Primus lists three elements: an "S" swirl that creates a larger area of engagement at the start of drilling, a larger curved cutting edge that lowers the manual load required, and a reverse taper with an extended flute that guides chips away from the surface.

The point is numbered by product: #3.5 on the OD-19 bonded washer series and #5 on the fiber cement, PUF panel, polycarbonate and wafer head fasteners.

Sealing Washer Technology

Several of these products depend on the washer as much as the screw. Deks sealing washers come in three forms on the Primus site. The TrueBlue EPDM washer is non-conductive and UV and ozone resistant, with a Deks blue line mark for traceability. The bonded washer has a metal face with EPDM encapsulating the metal support, a double seal under the head and against the sheet surface, and a 12 mm to 32 mm size range. The polycarbonate roof washer is made from a thermoplastic elastomer (TPE) and suits #12 and #14 gauge fasteners in 22 mm and 24 mm outside diameters.

Quality Assurance and Product Traceability

Primus's quality assurance page states that its screws are developed at an ISO 9001 compliant manufacturing plant in Taiwan, that each screw undergoes quality tests, and that a quality control unit monitors every batch shipped. The PC series is periodically evaluated on Kesternich and salt spray tests of 1,000 hours.

Product traceability is handled through labelling. Outer and inner boxes carry labels showing the size, the quantity packed per carton, the month of import and the batch series, and the page states compliance with AS 3566.2 Class 3.

Primus India's Focus on Fastener Quality and Innovation

The Research & Development page says Primus has combined tradition and innovation for over 20 years. It describes a high level of vertical integration, with all production processes in-house and key production machinery and tooling engineered by the company. The page frames the product path as an idea formed in India and a finished product made in Taiwan and India. Primus presents specialised components for the PEB and structural industry as a business area it has grown in recent years.

Frequently Asked Questions

What are specialised construction fasteners?

Specialised construction fasteners are screws engineered for a specific cladding, panel or substrate material instead of general fixing. They differ in head design, drill point, coating and washer. Primus India's specialised range includes bonded washer, fiber cement, PUF panel, polycarbonate sheet and wafer head fasteners.

What are polycarbonate sheet fasteners?

Polycarbonate sheet fasteners are self-drilling screws designed for fixing polycarbonate sheet into metal and timber. The Primus version uses an 8 mm hex washer head with a ø14.7 flange, a Trishul™ #5 drill point, a pilot-hole wing, PriSeal™ coating and a DEKS EPDM dome washer.

What are PUF panel fasteners?

PUF panel fasteners are screws for fixing insulated panel sheeting into metal. PUF panels are sandwich panels with an insulating foam core. The Primus product uses a hex washer head, a Trishul™ #5 drill point, PriSeal™ coating and an OD 19 bi-metal bonded washer.

What are fiber cement fasteners?

Fiber cement fasteners are screws that Primus designs for fixing non-asbestos sheeting into metal and timber. The product has an 8 mm hex washer head, a pilot-hole special wing for better grip, a Trishul™ #5 drill tip, PriSeal™ coating and an EPDM dome washer OD-25.

What is a wafer head fastener?

A wafer head fastener has a wide, low-profile head. Primus designs its wafer head fasteners for fixing clips to the secondary substrate, with the clips holding the roof. The product has a Trishul™ #5 drill point and PriSeal™ coating, and it is supplied in fine-threaded #10G and #12G sizes.

What is a bonded washer fastener?

A bonded washer fastener is a self-drilling screw with a sealing washer permanently attached beneath the head. The washer closes the gap between head and sheet. In the Primus OD-19 series, the washer combines a metal base with an EPDM sealing layer.

What does OD-19 mean in bonded washer fasteners?

OD-19 names the washer used in Primus's Pro Bonded Washer Series. The OD prefix is read as outside diameter, consistent with other washers named on the site, such as OD-25. Primus's technical page describes the OD-19 washer as a grey EPDM bonded washer with a 1 mm metal base and 3 mm of EPDM.

Why are sealing washers important?

Sealing washers close the gap between the fastener head and the sheet surface at each fixing point. Primus's Deks washers use EPDM, which the site describes as UV and ozone resistant, and some designs add a metal face for load distribution. The washer therefore affects both sealing and how the fastener bears on the sheet.

What is PriSeal™ Ruspert Polymer Coating?

PriSeal™ Ruspert Polymer Coating is Primus's tri-layered corrosion-protection finish: a metallic zinc layer, a chemical conversion film and a baked polymer top coat. Primus designs it to AS 3566 Class 3 and reports 1,000 hours of ASTM B117 salt spray testing and 7 Kesternich cycles to DIN 50018.

What is Trishul™ Drill Point technology?

Trishul™ is a patented Primus drill point for self-drilling fasteners. It combines an "S" swirl for a larger initial engagement area, a larger curved cutting edge and a reverse taper with an extended flute that guides chips away from the surface. Primus fits it across its specialised range.

Conclusion

Primus India's specialised construction fasteners follow one engineering pattern: a defined head and flange, a Trishul™ drill point, PriSeal™ coating, and a washer matched to the sheeting material. The OD-19 bonded washer, fiber cement, PUF panel, polycarbonate and wafer head fasteners each apply that pattern differently. For technical documentation, specification tables and catalogue downloads, visit the Primus India website.