THREADED PLATE

The ULAMEX threaded plate — also known as a sliding nut, channel nut, or T-nut — is a compact stainless steel insert that slides into the longitudinal T-slot channel of PV mounting profiles and provides a factory-threaded anchor point for DIN 912 socket-head cap screws. Once inserted and tightened, the threaded plate locks against the inner walls of the profile channel through friction and anti-rotation geometry, creating a secure bolted connection that can be positioned at any point along the rail length. This infinite adjustability is a fundamental advantage of T-slot mounting systems over pre-drilled alternatives, enabling installers to match any module width without profile modification.

Installation Guidelines

The threaded plate is inserted into the T-slot channel from the open end of the profile before the rail is fully assembled, or through a wider opening at any pre-existing access point along the rail. Slide the plate to the desired position along the channel, align it with the component to be mounted (clamp, bracket, roof hook adapter), and thread the DIN 912 socket-head cap screw through the component’s mounting hole and into the plate. As the bolt is tightened, the plate is drawn upward against the inner lips of the T-slot channel, locking it in position through a combination of clamping force and the anti-rotation profile of the plate edges.

Important: The variant A plate (27x13x4 mm) is designed for the narrower channel of the 40×40 mm PV profile, while the variant B plate (37.38×18.92×3.48 mm) fits the wider channel of the 80×40 mm PV profile. Using the wrong plate size will result in either an inability to insert (too large) or insufficient anti-rotation grip (too small). Always verify the profile cross-section before ordering.

Recommended tightening torque for M8 DIN 912 bolts into H17 stainless threaded plates: 12–16 Nm. Use a calibrated torque wrench — particularly important in PV installations where hundreds of identical connections must achieve consistent clamping force for structural integrity under wind and snow loads. Adding an EPDM washer between the bolt head and the mounted component improves vibration resistance and prevents bolt loosening over time.

Applications in Photovoltaic Mounting

• Clamp mounting — threaded plates anchor the M8 bolts that secure middle and end clamps to PV rails, allowing infinitely adjustable positioning along the profile to match any module width
• Roof hook connection — when the roof hook connects to the underside of the profile, a threaded plate inside the channel receives the fixing bolt from below
• Profile-to-profile joining — threaded plates inside one profile receive bolts from a perpendicular profile or cross-brace, creating rigid frame connections without welding
• Accessory mounting — cable management clips, earthing lugs, junction box brackets and other accessories bolt to threaded plates for clean, adjustable positioning along the rail
• PV triangle and ballast connections — threaded plates receive the M8 bolts from PV triangle brackets and ballast holders connecting to the profile channel

Material Properties

H17 stainless steel (1.4016 / AISI 430) is a ferritic chromium stainless steel with approximately 16–18% chromium content. Unlike austenitic grades (A2/1.4301, A4/1.4401), ferritic stainless steels contain no nickel, which gives them several distinctive properties relevant to PV mounting applications:

• Magnetic: 1.4016 is magnetic, which can be advantageous during installation — threaded plates can be held on magnetic tool tips for easier insertion into profile channels overhead
• Higher yield strength: Ferritic grades typically exhibit higher yield strength than austenitic A2 in the annealed condition, providing better resistance to thread stripping under bolt torque
• Good atmospheric corrosion resistance: The 16–18% chromium content creates a passive oxide layer sufficient for outdoor exposure in rural, suburban and urban environments
• Cost-effective: The absence of nickel makes 1.4016 significantly more economical than A2 (1.4301) while still providing genuine stainless steel corrosion resistance
• Lower thermal expansion: Ferritic stainless steels have a lower coefficient of thermal expansion than austenitic grades, reducing thermal stress at bolt connections through temperature cycling

For coastal or chemically aggressive environments, the standard H17 plate provides adequate protection for the service life of a typical solar installation (25–30 years). In extreme marine atmospheres (within 500 m of saltwater), consider upgrading all fasteners — including threaded plates — to A4 (1.4401) grade. Contact our team for availability.

Compatibility

ULAMEX threaded plates are precision-manufactured to fit the T-slot channels of the following profiles in the ULAMEX photovoltaic mounting range:

• PV Profile 40×40 mm — use variant A (27x13x4 mm)
• PV Profile 80×40 mm — use variant B (37.38×18.92×3.48 mm)

Compatible with all ULAMEX components that use M8 DIN 912 bolt fixation: aluminum clamps (mid, end, Click variants), roof hooks, PV triangle brackets, ballast holders, and mounting accessories.

Frequently Asked Questions

What is the difference between a threaded plate and a hammer-head bolt?

A threaded plate (sliding nut / channel nut) sits inside the profile channel and receives a bolt from outside. A hammer-head bolt (T-bolt) has an integrated head that sits inside the channel while the threaded shank protrudes outward. Both achieve the same result — a bolted connection at any point along the rail — but the threaded plate is preferred when the bolt must pass through the mounted component from outside, while the T-bolt is preferred when the stud needs to protrude for nut-and-washer assembly.

Can I insert threaded plates after the profile is already installed?

Yes, if the profile has an open end accessible for side-loading. If both ends are capped or joined to other profiles, you will need to use a spring-loaded channel nut or a pre-loaded T-bolt instead. Plan your threaded plate quantity and pre-load them before final rail assembly for maximum efficiency.

Which size do I need — variant A or variant B?

Variant A (27x13x4 mm) fits the 40×40 mm PV profile channel. Variant B (37.38×18.92×3.48 mm) fits the 80×40 mm PV profile channel. Check your profile cross-section before ordering. Using the wrong size will result in poor fit and compromised holding strength.

Is H17 stainless steel (1.4016) suitable for outdoor PV use?

Yes. 1.4016 ferritic stainless steel provides reliable atmospheric corrosion resistance for the 25–30 year service life of solar installations in rural, suburban and urban environments. Its higher yield strength compared to austenitic grades also provides superior thread-stripping resistance under torque loads.

Need threaded plates for your PV mounting project? Request a quote from ULAMEX — bulk quantities at B2B wholesale conditions with fast delivery across Europe. Complete your system with our full range of photovoltaic mounting components.