Steps to find Yeun Chyang Industrial Co., Ltd. listed on the GL Website:

Step 1: https://www.gl-group.com/webapp/wz_home_en.do
Step 2: Country: Choose TAIWAN
Step 3: Products: Choose Pipe Manufacturers

Click [SEARCH], will be able to find below information.
  

Approved Material Manufactures
 
List 2 - Pipe Manufacturers
 
Taiwan
Manufacturer
Inspection
Approval
Valid until
Yeun Chyang Industrial Co., Ltd.
270, Sec. 4, Jungshan Road

Chang-Hwa 		GL Kaohsiung
 WZ 1869 HH 0
 2011-08-19
Grade
Key
Supply
max. Thickness(mm)
max.Diameter(mm)
Remarks
1.4301(TP304), 1.4306(TP304L), 1.4401(TP316), 1.4404(TP316L)
acc. to EN 10217-7 (ASTM A312M);
equivalent grades acc. to JIS G3459 		GS-A S+Q 9.53 508 min. diameter: 13,72 mm; min. wall thickness: 1,65 mm