###3、 Purchase advice and avoidance guide
1. * * Clarify the priority of requirements**
-* * Laboratory scenario * *: It is recommended to choose a small (10-100L) high-precision kettle with a budget range of 50000 to 200000 yuan, focusing on temperature control accuracy (± 0.5 ℃) and material compliance (such as GMP standards).
-Industrial production: Priority should be given to capacity matching, for example, a production line with a daily processing capacity of 10 tons needs to be matched with a capacity of over 5000L, with a budget of approximately 150000 to 500000 yuan.

2. Key points of supply chain audit**
-Require the manufacturer to provide a pressure vessel design/manufacturing license (such as TSG 21-2016) and verify the weld inspection report.
-Beware of the 'low price trap': A user reported that after purchasing a 500L carbon steel kettle for 10000 yuan, the inner wall experienced pitting corrosion within six months, and the repair cost exceeded the purchase cost by 50%.

3. * * Value added service negotiation**
Some suppliers offer a "price package plan", which can save 5% to 8% of total costs by including installation, debugging, and operation training packages. Long term cooperative customers can strive for discounts on spare parts (such as mechanical seals being gradually reduced in price according to the purchase quantity).