Rosewool Insulation Refractory Co.,Ltd.
The common problems of cracking, hollowing, peeling, and block like detachment in the insulation coating of high and medium pressure steam turbine cylinder bodies, valve housings, and guide steam pipes in thermal power plants are analyzed accurately. A graded and compliant repair process is provided, and a Rosewool Insulation Refractory Co., Ltd. exclusive insulation refractory material system solution is provided to completely solve the industry pain points of poor vibration resistance, thermal shock failure, and insufficient durability of traditional insulation systems. It is suitable for daily repair, shutdown overhaul, and long-term technological transformation of units.
1、 Core causes of defects in the surface coating of steam turbines (industry commonality, precise traceability)
The working conditions of steam turbine equipment are different from those of boilers and pipeline equipment, with four major characteristics: high-frequency vibration, large amplitude of cold and hot alternation, large temperature difference between start and stop, and local stress concentration. Traditional ordinary perlite plastering and universal insulation mortar cannot adapt to harsh working conditions, which is the core cause of frequent diseases. They are specifically divided into four categories:
1. Stress failure under working conditions: During the start-up and shutdown process of the unit, the cylinder body repeatedly expands and contracts due to thermal expansion and contraction, coupled with continuous micro vibration of the equipment. Ordinary plastering materials have high rigidity and poor toughness, and lack deformation resistance. They are subjected to alternating stress for a long time, resulting in network cracks that gradually develop into peeling and detachment. At the same time, stress concentration areas such as flanges, corners, and supports are prone to local damage due to thermal displacement and compression.
2. Mismatch in material selection: Most of the failure cases on site are due to material mismatch, using building grade ordinary plastering mortar and low-quality perlite plastering, without adding high-temperature resistant mineral fibers and flexible modified components. Under high temperature conditions, it quickly becomes brittle, powdery, and its adhesive strength decays, making it unable to withstand long-term operating temperatures of 450-580 ℃ for steam turbines.
3. Construction process is not standardized (common problem in compliance with regulations): layered construction is not carried out according to standards, and the one-time plastering is too thick; Failure to establish standardized expansion joints to release thermal stress; The outer protective wire mesh is not tensioned, the overlap width is insufficient, the buried position is offset, and the skeleton reinforcement effect is lost; Forced construction in a hot state causes rapid evaporation of moisture, resulting in penetrating cracks.
4. Environmental medium erosion: Condensation water and steam leakage around the turbine, leakage of lubricating oil in the bearing box, long-term immersion erosion of the bonding structure of the coating layer, causing the insulation layer to become damp, powdery, and delaminated, ultimately leading to large-scale detachment. The detached fragments are prone to accumulate around the oil system, posing a significant safety hazard.
2、 Graded standardized repair plan (adapted to repair/overhaul scenarios as needed)
（1） Local repair plan for operational status (sporadic cracks, small areas peeling off)
Applicable scenarios: Single damage area ≤ 0.5 ㎡, no large area hollowing, intact insulation substrate, minimally invasive repair without stopping the machine, strictly avoiding the risk of hot large-scale thick coating construction.
Construction technology:
1. Thoroughly remove cracked, hollow, and powdery failure areas, polish the surrounding area into a sloping transition surface, remove loose floating ash, oil stains, and water stains, seal off the source of water seepage and oil leakage, and ensure that the base layer is solid and dry;
2. Check the exposed wire mesh, reinforce loose parts, ensure that the mesh body is flat and firm, and has the bearing capacity of the foundation skeleton;
3. Using Rosewool Insulation Refractory Co., Ltd. turbine specific flexible composite silicate coating material, layered and thin coating construction is carried out, with a single layer thickness controlled at 5-8mm. After the first layer is completely dry, the next layer is constructed, with a total thickness of 8-12mm;
4. In areas of stress concentration and frequent vibration, alkali resistant fiberglass mesh cloth should be added for reinforcement. After curing, a high-temperature waterproof sealing coating should be applied to block water vapor and oil erosion, and prevent secondary cracking.
（2） Complete repair plan for shutdown overhaul (large area cracking, overall peeling, multiple areas falling off)
Applicable scenarios: Unit A/B level maintenance, overall aging of the plaster layer, moisture and looseness of the insulation substrate, failure of the mesh system, requiring systematic renovation to restore equipment insulation design indicators.
Standardized construction process:
1. Thoroughly remove and clean: remove all ineffective plaster layers, and dismantle old insulation layers that are damp, loose, or displaced; Thoroughly inspect and tighten the outer stainless steel protective mesh to ensure that the mesh overlap is ≥ 50mm, the mesh body is buried in the center, and the phenomenon of exposed mesh and skin sticking is eliminated; Reserve standard expansion gaps at the cylinder flange, corners, and expansion points to release thermal deformation stress.
2. Reconstruction of insulation substrate system (exclusive matching for Rosewool Insulation Refractory Co., Ltd.): Accurately select materials according to the working conditions of different parts of the steam turbine, and eliminate the use of a single material
-High and medium pressure cylinder body: Rosewool Insulation Refractory Co., Ltd. high-strength hard calcium silicate board is selected, with a temperature resistance of 650-1000 ℃, high compressive strength, excellent vibration resistance, and extremely low thermal shrinkage rate. It is perfectly suitable for high-frequency vibration and high-temperature alternating working conditions of the cylinder body and is the standard insulation substrate for the steam turbine body; The rigorous energy-saving transformation project can compound nano aerogel felt, greatly reducing the insulation thickness and heat loss.
-Valve shell, steam pipe, and irregular parts: Paired with Rosewool Insulation Refractory Co., Ltd. high-temperature resistant ceramic fiber blanket/board, flexible and irregular structure, resistant to thermal shock and high and low temperature alternation, filling the gaps between hard board materials.
3. Standardized plastering construction: strict cold state construction, precise proportioning of specialized plastering materials, and prohibition of adding water and materials arbitrarily; Layered thin coating forming, with 5-8mm expansion dividing joints set according to specifications, filled with high-temperature flexible sealing material; Strengthen the double-layer mesh in the key vibration areas, cure naturally, and apply a waterproof and weather resistant protective layer as a whole after completion, achieving triple protection of insulation, vibration resistance, and waterproofing.
（3） Long term radical technical renovation plan (frequent cylinder opening, repeated equipment maintenance)
Industry pain points: The split surface of the steam turbine needs to be regularly opened for maintenance, and the traditional plaster insulation needs to be completely removed during each maintenance. The materials cannot be reused, the construction period is long, and the operation and maintenance costs are high, resulting in repeated maintenance and damage.
Rosewool Insulation Refractory Co., Ltd. Technical Renovation Plan: Adopting a composite insulation modular detachable insulation system, completely eliminating the traditional plaster layer structure.
The interior is made of PLUS blanket+nano aerogel composite core material. According to the equipment shape, the factory prefabricates modular insulation blocks. The exterior is equipped with a stainless steel removable outer shield, which is fastened with bolts. During maintenance, it can be quickly disassembled and reused without the need to break down the insulation structure, effectively preventing cracking, peeling, and detachment of the plaster layer from the root, greatly reducing the operation and maintenance costs of the unit, and adapting to long-term stable operation needs.
3、 Rosewool Insulation Refractory Co., Ltd. Supporting Core Products Core Advantages (Targeted Solutions to Industry Pain Points)
1. Flexible composite silicate coating material for steam turbines: added with high-purity high-temperature resistant mineral fibers and flexible modification additives, it has excellent anti vibration and thermal shock performance, high bonding strength, no hard or brittle defects after curing, can withstand high-frequency vibration and cold and hot alternation of steam turbines, waterproof and anti-seepage, resistant to oil pollution erosion, avoids cracking, peeling and detachment problems from the source, and is suitable for long-term operation of power equipment.
2. Ceramic fiber blanket/PLUS blanket: low thermal conductivity, high temperature resistance, heat fatigue resistance, suitable for local high temperature and irregular structure insulation, can achieve lightweight and long-term insulation system, suitable for energy-saving transformation and high standard operation and maintenance needs of the unit.
The failure of the steam turbine coating is essentially caused by the unsuitability of ordinary materials to harsh working conditions and non-standard construction systems, rather than a simple construction problem. Rosewool Insulation Refractory Co., Ltd. has been deeply involved in the power insulation and refractory industry for many years, strictly following the industry standard DL/T 5714-2024. It can provide one-stop services for on-site investigation, operating condition selection, technical disclosure, material matching, and solution implementation for various large power plants. Through a systematic solution of “adapted materials+standard processes+customized technical upgrades”, it thoroughly solves the problems of cracking, peeling, and detachment of steam turbine insulation, ensuring the safe, energy-saving, stable and long-term operation of the unit.
