Complete Analysis of Economizer Tube Grades HT150 and HT200 (GB/T 9439 Gray Cast Iron)

I. Meaning of Letters and Numbers

HT

Chinese pinyin abbreviation: Huī Tiě = Gray Cast Iron

Numbers 150 / 200

Represent the minimum tensile strength value, unit MPa

• HT150: φ30 test bar tensile strength ≥150MPa
• HT200: φ30 test bar tensile strength ≥200MPa

II. Core Performance Comparison

HT150

• Lower strength, excellent casting fluidity, easy to form
• Excellent vibration damping and thermal conductivity, lowest cost
• Not resistant to high temperatures, poor toughness, prone to cracking under load
• Applicable: Residential small boiler passive grate bars, ordinary furnace door bases, lightweight castings, non-pressure housings

HT200

• Higher strength and hardness than HT150, balanced overall performance
• Better wear resistance and thermal shock resistance than HT200, highest cost-performance ratio
• Applicable: Small and medium-sized chain grate bars, ash cleaning doors, observation doors, conventional boiler accessories (the most commonly used cast iron in the industry)

III. Selection Differences in the Boiler Industry

• Low temperature, light load, pursuing low cost → HT150
• Long-term operation, slight heat and wear, mainstream standard accessories → HT200
• High-temperature conditions (>650°C): neither is recommended; use RTSi5 / RQTSi5 heat-resistant cast iron instead

IV. Foreign Trade English Standard Designations

• HT150: Gray Cast Iron HT150
• HT200: Gray Cast Iron HT200