通风管道变形的主要原因可归纳为以下四类：
The main reasons for deformation of ventilation ducts can be summarized into the following four categories:
材料化学性质导致的膨胀：
Expansion caused by chemical properties of materials:
镁水泥自然养护时持续膨胀：线膨胀率0.1~0.2%，体积膨胀率约1%；
Continuous expansion during natural curing of magnesium cement: linear expansion rate of 0.1-0.2%, volume expansion rate of about 1%;
菱镁矿过烧产生的死烧MgO遇水生成Mg(OH)₂：体积膨胀120%；
The dead burned MgO produced by overburning magnesite reacts with water to form Mg (OH) ₂: the volume expands by 120%;
轻烧氧化镁中游离CaO水化膨胀90%，卤片SO₄²⁻与Ca(OH)₂反应生成石膏时固体体积增2倍以上。
The hydration expansion of free CaO in lightly burned magnesium oxide is 90%, and the solid volume of gypsum increases by more than twice when the halogen flakes SO ₄² ⁻ react with Ca (OH) ₂ to form gypsum.
热力学反应影响：
Thermodynamic reaction effects:
MgO-Mg-Cl₂-H₂O系统水化放热反应剧烈，大体积管道在高温环境下易产生结晶应力和热膨胀应力。
The hydration exothermic reaction of MgO-Mg-Cl ₂ - H ₂ O system is intense, and large volume pipelines are prone to crystallization stress and thermal expansion stress in high temperature environments.
施工与安装问题：
Construction and installation issues:
支吊架间距过大或固定不牢导致管道位移;
Excessive spacing between supports and hangers or inadequate fixation can cause pipeline displacement;
法兰垫片材质/厚度不达标、咬口缝密封不严引发漏风膨胀。
The material/thickness of the flange gasket does not meet the standard, and the sealing of the bite joint is not tight, causing air leakage and expansion.
外部因素：
External factors:
管道承压超软连接补偿量或支架移动引发变形。
Compensation for pressure bearing ultra soft connections in pipelines or deformation caused by support movement.
