Securing critical structural connections requires precision during installation and verifiable reliability for decades afterward. DuraSquirt DTI washers represent the pinnacle of Direct Tension Indicator technology, combining the stringent, calibrated accuracy of ASTM F959M with the long-term, weather-resistant visibility of high-visibility orange silicone. These advanced Squirtern DTI structural washers allow field crews to instantly verify proper compression loads during erection and empower maintenance teams to quickly audit bolt tension years later. To ensure your structural steel project is secured with fully certified, long-lasting indicators, explore the FULLERKREG DTI washer collection. For precise engineering specifications, compression load test reports, or bulk project quotes, please consult our technical sales team directly at sales@fullerkr.com.
What Is a DuraSquirt DTI Structural Washer?
A DuraSquirt DTI is a specially engineered, compressible steel washer featuring precisely calibrated raised protrusions (bumps) filled with a vibrant orange silicone. When the bolt is tensioned, the protrusions compress, forcefully extruding the orange silicone to provide an immediate visual indication that the required tension has been achieved.
Long-Term Visibility Benefits
- Remains visible for several years: Unlike temporary markings, the cured silicone provides a durable, multi-year visual record of proper installation.
- Withstands extreme elements: Highly resistant to heavy rain, high winds, and severe temperature fluctuations without degrading.
- Instant visual confirmation for maintenance: Facility engineers can perform rapid, long-term structural audits from a distance.
- Quick identification of untensioned bolts: Any bolt lacking the orange extrusion immediately stands out as missed or under-tensioned, preventing catastrophic failure.
Material and Manufacturing Specifications
| Specification | Details |
|---|---|
| Material Grade | ASTM F959M / Class 8.8 Equivalent |
| Dimensional Standard | ASME B18.2.6M |
| Coating | Mechanically Galvanized to ASTM B695 Class 55 |
| Heat Treatment | Through-hardened to max HRC 37 |
Why ASTM B695 Class 55 Mechanical Galvanizing?
- Excellent corrosion resistance: Provides robust protection suitable for outdoor and exposed structural environments.
- No hydrogen embrittlement: The mechanical plating process occurs at room temperature, eliminating the risk of hydrogen-induced delayed brittle fracture.
- Uniform coating thickness: Prevents thread interference and maintains predictable friction levels during tensioning.
- Compatibility: Fully compatible with high-strength AS1252 and ASTM F959M structural bolting assemblies.
Note: Traditional hot-dip galvanizing is strictly avoided for DTIs because the extreme heat can anneal the heat-treated protrusions, and the zinc buildup causes unpredictable dimensional growth and compression failure.
Compression Load Range by Diameter
Note: Values are strictly per ASTM F959M and must be verified using a Skidmore-Wilhelm calibration device prior to installation.
| Diameter | Number of Bumps | Min. Compression Load (kN) | Max. Compression Load (kN) |
|---|---|---|---|
| M12 | 4 | 49 | 59 |
| M16 | 4 | 91 | 109 |
| M20 | 5 | 142 | 170 |
| M24 | 5 | 205 | 246 |
| M30 | 7 | 326 | 391 |
| M36 | 8 | 475 | 570 |
Dimensional Specifications
| SKU | Item | OD / ID (mm) | Thickness (mm) | Bumps |
|---|---|---|---|---|
| [Auto] | M12 | 25.7 / 13.3 | 2.6 | 4 |
| [Auto] | M16 | 32.4 / 16.75 | 3.2 | 4 |
| [Auto] | M20 | 40.4 / 20.95 | 3.6 | 5 |
| [Auto] | M24 | 48.4 / 25.15 | 4.0 | 5 |
| [Auto] | M30 | 58.1 / 31.45 | 4.0 | 7 |
| [Auto] | M36 | 70.1 / 37.75 | 4.8 | 8 |
Recommended Installation Method
Step-by-Step Installation
- Inspect the hole: Ensure the structural hole is clean, properly aligned, and within standard dimensional tolerances.
- Position the DTI: Place the DTI under the nut, ensuring the protrusions (bumps) face away from the structural steel and toward the nut.
- Add structural washer: If the nut will rotate directly against the DTI, you must place a hardened structural washer between the nut and the DTI bumps.
- Snug the assembly: Tighten the bolts systematically to bring the steel plies into firm contact. Do not fully compress the DTI.
- Final tension: Tighten until the orange silicone is clearly visible and extruded from the DTI pockets.
Under-Head Installation
If project constraints require the DTI to be placed under the bolt head while the nut is rotated, an additional hardened structural washer MUST be placed under the nut to prevent the nut from digging into the steel substrate and causing false tension readings.
Critical Installation Factors
Hole Detail
- Uneven load distribution: Oversized or poorly aligned holes cause the DTI to sit unevenly, skewing compression.
- Silicone in voids: Oversized holes can swallow the extruded silicone, preventing visual verification.
- False readings: Slotted holes without proper plate washers cause the DTI to sink, resulting in false tension indications.
- Premature failure: Poor hole preparation can lead to localized yielding and loss of preload over time.
Storage Before Installation
- Prevents corrosion: Keeps assemblies dry and free from white rust.
- Maintains lubricant: Protects factory-applied nut lubricants from degrading or washing away.
- Protects threads: Prevents physical damage to bolt threads before installation.
- Keeps DTI in as-delivered condition: Ensures the silicone indicator remains intact and uncontaminated.
Lubrication
- Degraded factory lube: Apply additional lubrication if the factory coating has dried out due to poor storage.
- Galvanized friction: Mechanically galvanized bolts inherently possess higher friction and often require supplementary stick wax.
- Oxidation: Any signs of white rust or oxidation mandate immediate thread lubrication.
- Tool at capacity limit: If your impact or torque wrench is stalling before the DTI squirts, lubrication will drastically reduce the friction required to achieve tension.
AS1252 Compatibility
DuraSquirt DTI washers are engineered to be fully compatible with Australian AS1252 structural bolt assemblies. Their ASTM F959M verified compression loads align perfectly with high-strength structural requirements, providing erectors with an immediate, foolproof visual identification aid that far exceeds the reliability of traditional part-turn or torque methods.
Long-Term Visibility and Durability
- High winds: The cured silicone resists sheer forces and will not blow away over time.
- Heavy rain: Fully waterproof, preventing the indicator from dissolving or washing out.
- Extreme temperatures: Remains stable and visible without cracking or melting in severe climates.
- UV exposure: Formulated to resist fading under direct, prolonged sunlight.
These durability factors make DuraSquirt DTIs the ideal choice for critical, exposed infrastructure including bridges, transmission towers, power plants, and offshore platforms.
FAQ
-
What is the compression load range for an M24 DuraSquirt DTI?
An M24 ASTM F959M DTI requires a minimum compression load of 205 kN and a maximum of 246 kN to fully indicate. -
How long does the orange silicone indication remain visible?
The specialized silicone remains vibrant and intact for several years, allowing for long-term structural maintenance audits. -
What coating does a DuraSquirt DTI washer have?
They are mechanically galvanized to ASTM B695 Class 55, providing excellent corrosion resistance without the risk of hydrogen embrittlement. -
Why is hole detail critical to DTI washer installation?
Oversized or sloppy holes can cause the DTI to sink, distribute load unevenly, or swallow the silicone indicator, leading to false tension readings. -
Can DuraSquirt DTIs be used with AS1252 structural bolt assemblies?
Yes, they are fully compatible with AS1252 assemblies and provide a vastly superior visual verification method compared to part-turn tensioning. -
Where can I buy ASTM F959M DuraSquirt DTI washers with certified compression loads?
You can source fully certified, long-term visible indicators from the FULLERKREG DTI washer collection. For load test certificates and quotes, email sales@fullerkr.com.
Conclusion
When long-term structural integrity and maintenance verifiability are on the line, DuraSquirt DTI washers deliver unmatched performance. By combining precise mechanical compression indication with durable, multi-year visual evidence, they offer engineers and erectors ultimate peace of mind. Ensure your connections are secured right the first time, and verifiable for years to come.
Explore the FULLERKREG DTI Collection
Email us at: sales@fullerkr.com