高溫預制直埋保溫管從節(jié)約能源、降低造價、縮短施工周期、維護環(huán)境多方面來看，不只具有傳統(tǒng)地溝和架空敷設管道難以比較的技術和適用性能，而且具有顯著的社會效益和經濟效益，但一個的直埋供熱管道工程還必需具備設計合理、保溫管道質量牢靠1精心施工3個條件。由于直埋供熱技術在我國起步較晚，以上3個條件尚需不時完善。從工程理論中呈現(xiàn)的質量問題來看，應在設計和施工中特別留意以下幾個問題：
From the aspects of energy saving, cost reduction, construction period shortening and environment maintenance, the high temperature prefabricated directly buried heat preservation pipe not only has the technical and applicability performance that is difficult to compare between traditional trench and overhead pipeline laying, but also has remarkable social and economic benefits. However, a high quality directly buried heat supply pipeline project must also have reasonable design and reliable quality of heat preservation pipeline. Three construction conditions. Due to the late start of direct buried heating technology in China, the above three conditions need to be improved from time to time. From the point of view of quality problems in engineering theory, the following problems should be paid special attention to in design and construction:
高溫預制直埋保溫管
High Temperature Prefabricated Direct Buried Insulation Pipe
一、在設計和施工中，一定要真正了解供熱管道直埋敷設方式分為有補償直埋敷設及無補償直埋敷設兩種方式，的確控制兩種方式各自的工作原理，特性及其應用場所，以便在設計上合理選用，施工上平安、牢靠、經濟。
First, in the design and construction, we must really understand that the direct burial laying of heating pipelines can be divided into compensated direct burial laying and non-compensated direct burial laying. We must control the working principles, characteristics and application sites of the two methods, so as to make rational selection in design and safe, reliable and economical construction.
1 要控制概念：有補償直埋敷設方式，是經過管線自然補償和補償器(如方形和波紋管補償器)來處理管道熱伸長量的，從而使熱應力為小；無補償直埋敷設，簡單地說就是管道在受熱時沒有任何補償措施，而是靠管材自身強度來吸收熱應力。
First of all, we should control the concepts: there is a compensated direct burial laying method, which is to deal with the heat elongation of pipeline by natural compensation and compensator (such as square and bellows compensator), so as to minimize the thermal stress; non-compensated direct burial laying simply means that the pipeline does not have any compensation measures when heated, but absorbs the thermal stress by the strength of the pipeline itself.
2 無補償敷設方式的根本原理：在裝置管道時，給管道加熱到一定溫度，然后將管道焊接固定，當管道恢復到裝置溫度時(溫度降低)，管道預先接受了一定的拉應力。當管道通熱工作時，隨著溫度的升高，管道應力為零，當繼續(xù)升溫時，管道的壓應力增加，當溫度升到工作溫度時，管道的壓應力(熱應力)仍小于許用應力。這樣，管道能夠不用補償安裝而正常工作了。這種無補償方式應用第四強度理論，施工時需求對管道預熱，施工比擬費事，但國內外已有大量工程理論，理論計算牢靠，能確保平安。另一種無補償方式是近幾年由北京煤氣熱力設計院提出的計算辦法和應力分類采用安定性剖析，應用第三強度理論。這種方式充沛發(fā)揮鋼材塑性潛力，施工便當，無需預熱。
2. The basic principle of non-compensated laying method: when installing pipeline, heating pipeline to a certain temperature first, then welding and fixing pipeline, when the pipeline restores to the installation temperature (temperature decreases), the pipeline accepts a certain tensile stress in advance. When the pipeline is heated, with the increase of temperature, the stress of the pipeline is zero. When the temperature continues to rise, the pressure stress of the pipeline increases. When the temperature rises to the working temperature, the pressure stress (thermal stress) of the pipeline is still less than the allowable stress. In this way, the pipeline can work normally without compensation installation. This non-compensatory method applies the fourth strength theory, which needs to preheat the pipeline during construction. It is difficult to compare the construction. However, there are a lot of engineering theories at home and abroad. The theoretical calculation is reliable and can ensure safety. Another non-compensatory method is the stability analysis and the third strength theory for the calculation method and stress classification proposed by Beijing Gas Thermal Design Institute of China in recent years. In this way, the plastic potential of steel can be fully developed, and the construction is convenient without preheating.
3 兩種敷設埋設深度思索不同要素。
3. Consider the different elements of two laying depths.
高溫預制直埋保溫管
High Temperature Prefabricated Direct Buried Insulation Pipe
一是當肯定采用有補償直埋敷設方式時，埋設深度只思索由于空中荷載的作用不會毀壞管道的穩(wěn)定便可，從經濟、施工便當?shù)确矫嫠妓鳌．敳捎糜醒a償直埋敷設方式時，盡量淺埋，普通覆土厚度大于0．6米即可，且與管徑大小無關。
Firstly, when compensated direct burial is adopted, the burial depth only considers that the stability of pipeline will not be destroyed due to the action of air load, and considers from the aspects of economy and construction convenience. When compensated direct burial is adopted, shallow burial should be used as far as possible. The thickness of common overlying soil is more than 0.6 meters, and it has nothing to do with the diameter.
二是當采用無補償直埋敷設方式時，埋設深度要思索管道的穩(wěn)定請求，穩(wěn)定性當采用不預熱的無補預制償高溫預制直埋保溫管的操作應用直埋敷設管道時，主要與覆土厚度有關，普通比有補償埋得深，行，覆土厚度應與管徑大小成正比。
Secondly, when using non-compensated direct burial method, the burial depth should consider the stability requirements of pipelines. Stability when using non-preheated non-compensated pre-made high-temperature pre-buried insulating pipes directly buried pipelines, mainly related to the thickness of overlying soil. Generally, the depth of burying with compensation is deeper, and the thickness of overlying soil should be proportional to the diameter of pipelines.
4 設計中終究采用無補償敷設還是有補償敷設方式，準繩是直管道較長，中間分支較少，供熱介質不超越100℃時，應優(yōu)先選用無補償敷設方式，否則，應思索有補償敷設方式。詳細的熱網主干線應采用無補償敷設方式，而分支庭院管網則應采用有補償敷設方式，但目前有的設計者偏愛有補償敷設，應倡導優(yōu)化設計。
4. In the design, the non-compensatory laying or compensatory laying should be adopted. The criterion is that the straight pipeline is longer, the middle branches are fewer, and when the heating medium does not exceed 100 C, the non-compensatory laying method should be preferred. Otherwise, the compensatory laying method should be considered. Detailed heat network trunk lines should be laid without compensation, while branch courtyard pipeline networks should be laid with compensation. However, the current designers prefer to lay with compensation, and should advocate optimal design.
