ASME SA 249 Standard Specification for Welded Austenitic Steel Boiler, Superheater, Heat-Exchanger, and Condenser Tubes.
化学性质：
| 碳：不/a | Silicon: n/a |
| 锰：不/ | Nickel: n/a |
| 钾：N/A | Chromium: n/a |
| 硫：不/a | Molybdenum: n/a |
Mechanical Properties:
ASTM A249规格涵盖了名义壁厚度的焊接管和由奥氏体钢制成的严重的焊接管。
更具体地说，ASTM A249规范旨在用于以下用途：
Upon complete, the material shall :
生产优质的ASTM A249和ASME SA249压力管不仅仅需要在产品上使用模板。
It requires a manufacturing process and a quality system that not only provide an excellent weld, but also condition the weld through proper cold working (forging) and heat treating (annealing) processes so that it closely approximates the structure and properties of the base metal. Only then will the tube have the proper corrosion resistance, stability at temperature, and mechanical properties needed for the most demanding applications.
仅应使用融合焊接工艺来生产高质量的不锈钢，双链和合金管，将用于苛刻或关键的应用。
过程：仔细查看
融合工艺会产生一块熔融的金属水坑，该金属湿润两个钢边缘，并被允许固化以产生单个焊接。气钨电弧焊接（GTAW）通常称为钨惰性气（TIG）焊接，是最常用的过程。还使用了等离子体弧焊接（PAW），并且经常被缩写为血浆焊接。
A less common process is laser beam welding (LBW), which uses light energy to create a molten puddle and the resultant weldment. GTAW and plasma welding are the most forgiving of the common welding methods and can produce an excellent-quality weld most easily.
Figure 1是激光焊接316L管的显微照片。该管尚未锻造或退火。注意与基本材料相比，焊缝的铸造结构。
The comparatively small weld puddle created by laser beam welding makes it difficult to achieve a robust manufacturing process. The strip-forming process and weld joint configuration must be very precise, and this often requires strip edge preparation.
冷工作（锻造）ASTM和ASME焊接压力管规范需要焊接区域。必须在内部和外部锻造管以实现正确的特性。
焊缝是具有树突结构的铸件，应将其重结合到碱金属的等位晶粒结构。
Both sufficient cold work and proper annealing are necessary to complete the recrystallization process. Annealing often is done on the tube mill and in a hydrogen atmosphere, which reduces surface oxide films and heat tint from welding. The result is a solution-annealed, recrystallized weld and a clean tube that forms a naturally occurring passive surface oxide film as soon as it leaves the annealer and is exposed to oxygen in the atmosphere.
离线氢气明亮的退火器可用于需要特殊退火循环的合金或规格。
Figure 2显示正确焊接，锻造和退火的管截面的显微照片。请注意，焊缝的晶体结构与碱金属的结构几乎相同。
Quality Control
管道的质量控制检查和测试应广泛，可以归类为无损测试，机械测试或腐蚀测试。ASME和ASTM压力管规范要求对产生的每次管道进行静水压力测试或无损电测试。
无损和机械测试。在作者公司执行的无损涡流测试中，检查了管是否缺陷，并用墨水喷雾标记，并在其中注明了缺陷。可检测到的缺陷可以植根于原材料问题，例如层状或带状层中的其他缺陷，或制造过程中的问题，例如焊接渗透或完整性或锻造。所有磨坊操作员均应接受ASNT SNTC1A 1级或更高层的涡流无损测试技术的培训和认证。
Dimensional inspection is performed online at the mill to ensure conformance to ASTM, ASME, company, or customer requirements, including dimensional tolerance of the tube outside diameter (OD), wall thickness, and length. Equipment used ranges from tape measures to laser micrometers.
ASTM和ASME压力管规范需要以指定的间隔对随机管样品进行破坏性测试 - 例如，每个生产批次每1,500英尺（450米）（450米）。这些必需的机械操作测试包括扁平（无缝管的耀斑测试），法兰和反向弯曲测试（请参阅Figure 3）。这些测试是对具有纵向取向的焊接的样品进行的。认真的供应商还可以在横向方向上以焊缝进行这些测试，以作为额外的保证。
In addition, room-temperature tensile and hardness tests are required to evaluate the material properties of the tube and to provide assurance of conformance to pressure vessel design criteria.
腐蚀测试。客户可以要求腐蚀测试以评估晶间腐蚀抗性，发现对服务敏化的敏感性，测量相对于基础/母体材料的焊缝衰减特性，或确定特定环境中对特定或一般腐蚀攻击的敏感性。
It is important to remember that each type of corrosion test is designed to give some indication of an alloys or alloy family's suitability for a specific application environment and that a particular test may not be appropriate to a particular alloy or application. Therefore, fabricators and producers should be careful when specifying corrosion testing requirements.
例如，ASTM A249-S7焊接衰减测试被认为是可靠的腐蚀测试，但实际上，该测试中使用的酸适用于不到1％的现实运营环境。其他测试（例如ASTM A262实践A＆E）对于测试一般腐蚀可能更实用。
Figure 4是在激光焊接的304L管上执行的焊接衰减测试的扫描电子显微镜图像ASTM A249-S7。注意焊缝的攻击少于碱金属，导致焊缝衰减比为0.84。比率是焊缝厚度的变化除以基本材料厚度的变化。在此示例中，焊缝在测试过程中的攻击小于碱金属。
Raw material specifications are an important factor in achieving a high-quality welded tube. Physical properties of the strip, as well as its chemistry, are specified and controlled tightly to ensure a quality tube. For example, small additions of sulfur have been known to improve weldability, but excessive amounts may harm the ductility and formability of the product.
In conclusion, making a good-quality pressure tube starts with a well-specified raw material. It also requires a good fusion-type weld, cold work of the weld area, heat treatment, and, of course, close dimensional control of the forming and finishing processes. Last but not least, testing methods must be topnotch to ensure a top-quality product.
不锈钢是建筑物和工程行业中最标准化的材料之一。
