In 2022, we provided a variety of gaskets and materials for the restoration of a steam locomotive boiler that initially entered service in 1919 and was undergoing the process of returning to steam. Today's industrial boilers require significantly more gaskets as modernity places ever-higher demands on them.
However, the fundamental nature of the process and gasket types has remained unchanged since the Renishaw emitted its inaugural steam cloud over a century ago. Indeed, numerous manufacturing techniques employed at our factory for producing gaskets, whether for contemporary or heritage steam boilers, have stood the test of time, having been in use for decades. Class, as they say, is permanent.
The internal mechanisms of steam boilers pose challenging conditions. When choosing gasket materials, it is crucial to meticulously evaluate their ability to withstand the temperature, pressure, and resistance to fluids required for their designated role within the boiler system. Proper selection and placement of gaskets are essential throughout the entire steam production and conveyance process. Let's explore some of the most commonly used gaskets in this context.
Boiler Seal Gaskets
Boiler steam gaskets are typically deployed in key locations, such as flange connections, valve seats, and boiler doors, where potential points of steam leakage exist. The gasket's effectiveness relies on its ability to form a reliable seal while accommodating thermal expansion and contraction, vibration, and mechanical stresses associated with the dynamic nature of boiler operations.
Historically, compressed asbestos was a commonly used material due to its ability to withstand heat and pressure. However, modern alternatives have emerged, including Boiler Seal gaskets, for which Dobson is the exclusive supplier in the UK. These high-quality EPDM polymer gaskets combine high-temperature capability with the sealing resilience of elastomeric materials, making them the ideal boiler door seal for both modern and heritage industrial boilers.
Spiral Wound Gaskets
On the fire side of the boiler system, the ability to perform at very high temperatures is paramount and spiral wound gaskets excel due to their ability to withstand extreme conditions. Introduced to the petrochemical industry in 1912, they were developed to address the growing need for leak-resistant seals in applications characterised by escalating and variable temperatures and pressures. Constructed in a spiral fashion by winding a V-shaped metal strip for structural integrity and resilience, with a softer filler material for flexibility and sealing effectiveness, this combination also enhances the gasket's resistance to chemical attacks and thermal cycling.
The materials used can vary, and at Dobson Gaskets we manufacture these gaskets in a range of configurations to meet customer requirements. In the harshest working environments such as industrial boiler applications, metal strips of Stainless Steel, and the filler material Mica, are often the ideal configuration as both materials can operate at temperatures reaching 1000°C, while Mica is also very resistant to a wide array of chemicals.
Glass Ladder Tape
Another excellent solution for fire-side boiler sealing, Glass Ladder Tape can withstand temperatures above 550°C and has good resistance to oils, solvents and most chemicals. Many may recognise this sealing material from their oven or wood-burning stove doors at home. Crafted from woven glass fibres, the tape is precision-engineered, featuring a ladder-like weave pattern that imparts both flexibility and structural integrity.
Its inherent thermal resistance stems from the glass fibre composition, enabling the tape to withstand extreme temperatures without compromising its insulating properties. This makes glass ladder tape an ideal solution for applications such as boiler gaskets, expansion joints, and seals in industrial settings. The tape's low thermal conductivity efficiently mitigates heat transfer, providing effective insulation against both radiant and convective heat. Moreover, its resistance to chemical corrosion ensures longevity in challenging operating conditions.
Taylor Ring Gaskets
Taylor corrugated gaskets are meticulously designed to ensure the robust sealing of valves that process steam and hot water. Crafted from thin sheet metal formed into embossed concentric rings, these gaskets serve as a resilient barrier against the demanding conditions of high temperatures and pressures prevalent in steam boiler operations. The corrugated structure of these gaskets not only reinforces their resilience but also facilitates adaptability, accommodating jointing compounds or cord fillings for optimal sealing performance.
Whether configured for narrow or full-face flanges, Taylor Ring Gaskets exhibit a versatility that aligns seamlessly with the diverse requirements of steam boiler installations. At Dobson Gaskets, we understand that the choice of metal type and thickness, alongside meticulous considerations of corrugation pitch and depth, is pivotal in determining the gasket's overall resilience and efficacy in maintaining a leak-proof seal over time.
Reflex Gaskets
Reflex Gaskets are commonly used to create a watertight seal on level gauges used in steam processing applications. Configured from borosilicate glass, which has high chemical resistance and a low thermal expansion, they are tempered to resist high pressure and temperature. Reflex glass features a set of V-shaped refractive grooves which when in contact with the liquid and steam in the level gauge work to show the liquid level. They serve as a reliable means of monitoring liquid levels, especially in high-pressure steam boiler systems, where precise control is essential.
Dobson Gaskets extends its manufacturing expertise to include cushion joints made from Novus 34 (located on the dry side of the gauge) and sealing gaskets (on the wet side) crafted from Flexigraf FGS3, a graphite laminate gasket reinforced with a tanged stainless steel core. This combination ensures superior creep resistance and remarkable tolerance to high-pressure steam environments. The unique composition of these gaskets enables clear differentiation between liquid and vapour phases, providing operators with a prompt and precise means to assess water levels.
The selection above is by no means exhaustive, with other gasket configurations available for applications throughout the modern or heritage industrial boiler system. At Dobson Gaskets, we can provide a wide range of gaskets to suit every application, customised to meet the precise requirements of the customer. To find out what your best options are, contact one of our specialists today.