Operational Safety in Power Stations:
The Engineering Case for BIRKOSIT® & FILLING® Sealing Compounds

Why Sealing Matters in Power Stations

Turbine components in steam and gas power plants operate under conditions that push the boundaries of materials science. High pressures, extreme temperatures, cyclic mechanical stresses, and chemically aggressive environments combine to create maintenance challenges that have no simple defaults.

Among the most consequential — and most often underestimated — of these challenges is the sealing of turbine parting plane flanges and pressure-area joints.

When a turbine is taken offline for scheduled maintenance and the casing is split along the horizontal parting plane, what engineers find is rarely what specifications assume. Sealing surfaces exhibit corrosion from moisture and steam ingress, erosion from high-velocity particulate contact, fretting damage from thermal cycling, and mechanical damage sustained during dismantling.

The consequence of getting this wrong is not a minor efficiency penalty. It is unplanned outage, progressive leakage that widens under pressure, and — in the worst cases — catastrophic failure driven by corrosion that develops invisibly over years of operation.

Selecting the right sealing compound is therefore not a procurement decision. It is an engineering decision with direct implications for plant safety, reliability, and cost.

The Hidden Chemistry Risk

The most dangerous aspect of incorrect sealing compound selection is that the damage it causes is hidden. It does not manifest immediately as a visible leak or an obvious failure. It initiates corrosion at a microscopic level — and accelerates under exactly the conditions that turbine flanges experience during operation.

The mechanism

Sealing compounds that contain halogens — chlorine, fluorine, or bromine — or sulphur compounds behave predictably under high temperature and steam exposure. They release reactive species that penetrate metal grain boundaries and initiate stress corrosion cracking (SCC). The process is self-reinforcing: micro-cracks concentrate stress, which propagates the crack under operational load, which exposes more fresh metal surface to the corrosive environment.

Why this is not widely understood

Many sealing products are designed for general industrial use — flanged joints in piping systems, static pressure vessels, and similar applications. These environments do not combine high temperature, dynamic load cycling, steam chemistry, and the extended service intervals typical of turbine operation. A product that performs acceptably in a pipe flange application may be actively harmful in a turbine casing joint.

The requirement for turbine-grade sealing compounds is therefore not a matter of incremental quality — it is a fundamental difference in design intent and material chemistry.

BIRKOSIT® — Design Philosophy and Certification

BIRKOSIT® was developed in 1952 by the German chemical manufacturer A. I. Schulze, in direct collaboration with Siemens. The product was designed from the ground up for one specific application: the sealing of turbine casings and high-pressure flanges in steam and gas power generation equipment.

This is not a general-purpose sealant that was later adapted for turbine use. Every aspect of its formulation reflects the operational constraints of turbine environments.

Chemical certification

A. I. Schulze provides formal chemical certification with every supply of BIRKOSIT®, confirming:

• Contains no sulphur
• Contains no halogens — no chlorine, fluorine, or bromine
• Contains no hazardous or corrosive substances
• Is not solvent-based — formulated on a linseed oil carrier

This certification is a standard part of the product supply, not an optional document. It gives maintenance engineers and plant managers a defensible, documented basis for their material selection decisions.

Technical Capabilities

BIRKOSIT® is rated for continuous service under conditions that represent the upper range of industrial turbine operation.

Media resistance

BIRKOSIT® maintains sealing integrity in contact with:

• Hot steam, hot air, hot and cold water
• Light fuel oils and lubricants
• Crude oil and natural gas

Proven operational heritage

BIRKOSIT® has been in continuous use on Siemens turbines for over 50 years. This is not a case study claim — it is a documented operational record. The compound has been validated through actual service cycles on equipment operating at full design loads in commercial power plants.

It is, to our knowledge, the only sealing compound that was developed exclusively for turbine flange applications from its inception.

The FILLING® Product Range

While BIRKOSIT® is suited for well-prepared, smooth sealing surfaces, real maintenance environments routinely present a wider range of surface conditions. To address this, FILLING Products GmbH — the product family to which BIRKOSIT® belongs — introduced three purpose-engineered variants that cover the full spectrum of surface damage encountered in turbine overhauls.

Product selection is determined by one factor: the actual measured gap range on the surface being sealed.

All three products carry GE approval and share the same core chemistry as BIRKOSIT® — halogen-free, sulphur-free, non-solvent based, and certified by the manufacturer.

Product Selection Decision Framework

The selection process begins with a documented surface assessment after casing opening. Measure the gap at multiple points using feeler gauges, assess the extent and depth of corrosion or erosion, and use the following framework to select the appropriate product.

When to use sealing compounds vs. machining

Machining remains the correct response when surface gaps exceed 1.0 mm, when structural damage requires material removal for load-bearing integrity, or when original design specifications require a precisely machined interface. In all other cases — which represent the majority of real-world maintenance scenarios — the FILLING® range provides a faster, lower-risk, and cost-effective alternative.

Application Procedure

Correct surface preparation is the single most important factor in achieving full sealing performance. The compound performs its function through intimate contact with the metal surface — contamination, moisture, or grease residue will compromise the seal.

Surface preparation requirements

• Surface must be dry, clean, and fully degreased
• Recommended surface finish: Ra 0.8–1.2 µm
• Smooth or lightly structured metal surface — no loose material or sharp edges
• No additional gaskets required — the compound is the sealing element

Two-step application for multi-product scenarios

When surface condition requires both FILLING® 2000 (spot areas) and FILLING® Basic or 1000 (remaining surface), follow this sequence:

1. Step 1 — FILLING® 2000: Apply to damaged areas with gaps up to 1.0 mm. Spot application only on selected cavities and erosion zones.
2. Step 2 — FILLING® 1000 or Basic: Apply over the entire remaining sealing surface. Follow product selection based on overall surface condition.

The compound remains elastic after assembly — it does not cure rigid. This allows it to accommodate thermal expansion, contraction, and slight differential movement between casing halves during operation, which is a critical property for long-term sealing integrity across the turbine's temperature cycling range.

Service Life and Storage

The 10-year guaranteed service life aligns with standard turbine major overhaul intervals, meaning a correctly applied seal should not require re-treatment between planned maintenance cycles. This directly reduces lifetime maintenance cost and eliminates unplanned re-entry into the casing.

Storage requirements are straightforward: keep containers sealed when not in use, store at ambient workshop temperature, away from direct sunlight. No refrigeration, no specialist storage conditions.

Industry Acceptance in India

BIRKOSIT® and FILLING® products have been evaluated and accepted by the leading turbine manufacturers and power generators operating in India. Acceptance by these organisations reflects the technical assessment of their engineering and maintenance teams — these are not commercial endorsements but engineering qualifications.

TechMRO Inc. is the authorised distributor for FILLING Products in India, providing technical support, product selection guidance, and supply across the country.

Conclusion

The selection of a turbine sealing compound is not a commodity procurement decision. It is a materials engineering decision with direct consequences for plant safety, operational availability, and long-term maintenance cost.

BIRKOSIT® and the FILLING® range address this requirement with a product family that was designed specifically for turbine applications, is chemically certified to be free of corrosion-initiating substances, and has an operational track record spanning more than seven decades on commercial power generation equipment.

The decision framework is clear: assess the actual surface condition, select the product that matches the measured gap range, and apply correctly. The result is a sealing solution that meets the operational demands of modern steam and gas turbines — without the downtime cost, tolerance risk, and logistical complexity of machining.