Boiler Refractory and Code

🔥 1. API 936 – Refractory Installation Quality Control – Inspection and Testing Monolithic Refractory Linings and Materials

Purpose:

API Standard 936 provides the minimum requirements for quality assurance and control of monolithic refractory installations — from material selection, mixing, installation, curing, to drying.

This standard ensures that refractory linings (castables, plastics, gunnite, etc.) are installed safely, consistently, and perform reliably in high-temperature services (like furnaces, reformers, or boilers).

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Scope & Coverage:

• Applies to monolithic refractories, not brick linings.

• Covers specification, testing, installation, curing, and drying procedures.

• Emphasizes quality control and inspection requirements.

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Key Areas in API 936:

Section	Description
Material Qualification	Defines requirements for raw materials (castables, binders, aggregates) to ensure they meet chemical & physical specs.
Pre-Installation Checks	Inspection of forms, anchors, mixing water, environment, and equipment before lining.
Mixing & Placing	Specifies methods for mixing castable materials, gunning, ramming, or shotcreting.
Curing	Defines required curing time, humidity, and temperature before drying.
Dry-Out Procedures	Controls heating-up schedule to remove moisture safely and avoid spalling or cracking.
Testing & Acceptance	Requires compressive strength tests, density, permeability, and visual inspection.
Inspector Qualification	API 936 also defines qualification for refractory inspectors (API 936 certification).

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Typical Application Areas:

• Fired heaters

• Reformers and furnaces

• Fluid catalytic cracking units (FCCU)

• Boiler combustion chambers

• Incinerators

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Why It Matters:

Poor refractory installation is a major cause of premature failure in fired equipment. API 936 ensures:

• Consistency in material quality

• Correct installation technique

• Controlled curing and dry-out

• Documentation for traceability

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🔧 2. API 982 – Refractory Linings in Fired Process Equipment in General Refinery and Petrochemical Service

Purpose:

API 982 gives engineering and design guidance for refractory linings in fired process equipment, focusing on material selection, design, and application to achieve long-term performance and reliability.

While API 936 focuses on installation quality, API 982 focuses on design and material engineering.

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Scope & Coverage:

• Provides best practices for selection, design, and maintenance of refractory systems.

• Applicable to fired heaters, reformers, incinerators, sulfur recovery units (SRU), and similar high-temperature equipment.

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Key Topics in API 982:

Section	Description
Refractory Material Selection	Guidance on selecting correct type (dense, insulating, low-cement, etc.) based on service condition.
Lining Design	Includes thickness, anchoring system, expansion joints, and thermal stress considerations.
Thermal Performance	Thermal conductivity, heat loss calculations, and temperature profiles.
Mechanical Design	Addresses stresses due to thermal expansion, vibration, or structural loads.
Anchor Design	Selection of anchor materials, shapes, spacing, and welding practices.
Installation Practices (reference to API 936)	Advises following API 936 for QA/QC and inspection.
Maintenance and Repair	Inspection intervals, damage mechanisms (spalling, chemical attack, erosion), and repair recommendations.

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Differences Between API 936 & API 982

Aspect	API 936	API 982
Focus	Installation quality, inspection, testing	Design, engineering, material selection
Users	Refractory inspectors, contractors	Engineers, designers, plant reliability teams
Covers	Procedures for mixing, curing, testing	Thermal, mechanical, chemical design aspects
Stage	Construction / QA phase	Design / Engineering phase
Certification	API 936 Inspector certification available	No certification program

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Summary Analogy:

• API 982 → “Design the refractory system correctly.”

• API 936 → “Install and test the refractory system correctly.”

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