Name: Risers / Conductors
Brand: ZC Steel Pipe

Standard

API 5L, API 5CT, SY/T 6558-2003, SY/T 10031-2000, SY/T 10030-2004

Grades

8 grades

Size Range

OD 20"–36" and 850–933 mm; pipe length ~12 m

Applications

→ Offshore platform drilling — isolating the wellbore from seawater during exploration and development drilling
→ Conductor pile installation — jack-up and fixed-platform wells using hammer-driven conductor with four-start threaded connector
→ Riser string assembly — rapid connection and disconnection using single circlip or four-start threaded connectors for float-over and jack-up operations
→ Platform and FPSO exploration wells — conducting fluid and pressure between drill floor and seabed wellhead

Physical & Mechanical Properties

Property	Value / Range
Pipe grade (API 5L)	Gr.B, X42, X52, X56, X60, X65, X70 (PSL-1 and PSL-2)
Pipe grade (API 5CT)	K55 (PSL-1 and PSL-2)
OD range	20″, 22″, 24″, 26″, 30″, 36″ and 850–933 mm
Wall thickness	1.0″ (25.4 mm) typical; 30 mm, 38 mm, 45 mm for metric sizes
Pipe length	Approximately 12 m
Standards (pipe body)	SY/T 6558-2003, SY/T 10031-2000, SY/T 10030-2004
Connector types	Single Circlip, Double Circlip, Single Threaded, Four-start Threaded
Platform compatibility	Jack-up, floater, and fixed platforms

API 5CT Mechanical Requirements by Grade

Grade	Min–Max Yield MPa / ksi	Min Tensile MPa / ksi	Max Hardness	Heat Treatment
H40	276–552 / 40–80	414 / 60	—	None required
J55	379–552 / 55–80	517 / 75	—	None required
K55	379–552 / 55–80	655 / 95	—	None required
N80-1	552–758 / 80–110	689 / 100	—	Normalise or Q+T
N80Q	552–758 / 80–110	689 / 100	—	Q+T only
L80-1	552–655 / 80–95	655 / 95	23 HRC	Q+T only
L80-3Cr	552–655 / 80–95	655 / 95	23 HRC	Q+T only
L80-9Cr	552–655 / 80–95	655 / 95	23 HRC	Q+T only
L80 13Cr	552–655 / 80–95	655 / 95	23 HRC	Q+T only
R95	655–758 / 95–110	724 / 105	—	Q+T only
C90	621–724 / 90–105	689 / 100	25.4 HRC	Q+T only
T95	655–758 / 95–110	724 / 105	25.4 HRC	Q+T only
P110	758–965 / 110–140	862 / 125	None	Q+T only
C110	758–828 / 110–120	793 / 115	29.0 HRC	Q+T only
Q125	862–1034 / 125–150	931 / 135	None	Q+T only

API 5CT grades manufactured and supplied by ZC Steel Pipe. Grade selection is driven by well depth, H₂S environment, and pressure containment requirements.

Grade	Yield MPa / ksi	Tensile MPa / ksi	Max Hardness	H₂S Service	Typical Application
K55	379 / 55	655 / 95	—	✗ No	Surface casing, conductor

Sour Service Grade Selection

Procurement Note — H₂S Grade Selection Never substitute P110 or Q125 for a sour-service grade based on cost or availability pressure. NACE MR0175 hardness limits exist to prevent sulphide stress cracking — a brittle fracture mode with no ductile warning in H₂S environments. The correct escalation path is L80 → T95 → C110 depending on H₂S partial pressure and well depth.

Condition	Correct Grade
Mild sour, moderate pressure	L80-1 PSL-2 (+ SR16 HIC test if required)
Moderate sour, high pressure	T95 Type 2 PSL-2 with NACE qualification
Severe sour, high pressure / HPHT	C110 PSL-2 with full NACE + Charpy
Deep HPHT, sweet (no H₂S)	P110 PSL-2 or Q125 PSL-2

Pipe Body Grades

Standard	Grade	PSL	Typical Application
API 5L	Gr.B	PSL-1 / PSL-2	Conductor pipe for shallow water and platform wells
API 5L	X42	PSL-1 / PSL-2	Standard conductor for moderate water depth
API 5L	X52	PSL-1 / PSL-2	Conductor and riser for moderate to deep platform wells
API 5L	X56	PSL-1 / PSL-2	High-strength conductor for deep conductor strings
API 5L	X60	PSL-1 / PSL-2	Higher-strength conductor for deep offshore applications
API 5L	X65	PSL-1 / PSL-2	High-strength conductor for demanding offshore environments
API 5L	X70	PSL-1 / PSL-2	Highest-strength API 5L conductor grade
API 5CT	K55	PSL-1 / PSL-2	Surface conductor / conductor casing equivalent

Pipe Body Standards

API 5L — Line pipe specification — Gr.B through X70, PSL-1 and PSL-2
API 5CT — Casing and tubing specification — K55 for conductor casing service
SY/T 6558-2003 — Offshore oil and gas wells ice-resistant riser design and manufacturing practices
SY/T 10031-2000 — Structure under cold conditions and sea — recommended practices for planning
SY/T 10030-2004 — Planning, design and construction of fixed offshore platforms — recommended practices

Four quick-connect conductor connector types. Single Circlip, Single Threaded, and Four-start Threaded connectors have full specification data below. Double Circlip connector is available — contact for specifications.

Single Circlip Connector — Specifications

Size	Conn OD (mm)	Conn ID (mm)	Pin L (mm)	Box L (mm)	Asm L (mm)	Anti-Rot	YS (MPa) ≥	TS (MPa) ≥	Crush (MPa) ≥	Burst (MPa) ≥	Test T (kN) ≥	Seal	Circlips
20″×1″	593	457	235	275	304	Anti-rot pin	325	470	35.1	32.6	3500	Seal ring	1
22″×1″	643.8	508	245	285	314	Anti-rot pin	325	470	32.5	29.7	3500	Seal ring	1
24″×1″	695	559	260	305	329	Anti-rot pin	325	470	30.2	27.8	3500	Seal ring	1
26″×1″	745	609	295	350	387	Anti-rot pin	325	470	28.3	25.9	3500	Seal ring	1
30″×1″	847	711	295	350	387	Anti-rot pin	325	470	25.0	22.8	3500	Seal ring	1
30″×1″ (2)	911	711	350	418	282	Anti-rot pin	590	785	61.2	31.2	3500	Seal ring	2
850×45	933	760	350	418	486	Anti-rot pin	325	470	28.7	26.5	3500	Seal ring	1
850×38	933	760	350	418	486	Anti-rot pin	325	470	28.7	26.5	3500	Seal ring	1
850×30	933	760	350	418	486	Anti-rot pin	325	470	28.7	26.5	3500	Seal ring	1

Note: The second 30″×1″ row (911 mm OD) has 2 circlips and higher strength (YS 590 MPa). Assembled length 282 mm for this row — please verify with ZC before ordering.

Four-start Threaded Connector — Specifications

Size	Thread	Conn OD (mm)	Conn ID (mm)	Pin L (mm)	Box L (mm)	Asm L (mm)	Torque (lbf·ft)	Speed	Anti-trip	YS (MPa) ≥	TS (MPa) ≥	Crush (MPa) ≥	Burst (MPa) ≥	Test T (kN) ≥	Seal
20″×1″	1-start	550	457	250	250	342	22000–28000	≤6 turns	Selflock	735	930	70	64	3920	Seal ring
20″×1″	4-start	550	457	250	250	342	19000–24000	¼–¾ turn	Lock piece	735	930	70	64	3920	Seal ring
22″×1″	4-start	600	509	260	260	362	19000–24000	¼–¾ turn	Lock piece	735	930	64	58	3920	Seal ring
24″×1″	4-start	610	515	252	270	342	22000–28000	¼–¾ turn	Lock piece	735	930	58	54	3920	Seal ring
24″×1″	1-start	610	515	252	270	342	32500–40000	≤6 turns	Selflock	735	930	58	54	3920	Seal ring
26″×1″	4-start	705	610	270	270	374	24000–30000	¼–¾ turn	Lock piece	735	930	54	50	3920	Seal ring
30″×1″	4-start	815	712	325	325	452	27000–32500	¼–¾ turn	Lock piece	735	930	47	43	3920	Seal ring
36″×1″	4-start	980	863.6	325	325	450	32500–40000	¼–¾ turn	Lock piece	735	930	36	35	3920	Seal ring

Double Circlip Connector

Double Circlip connector available — contact for specifications. Spec sheet pending.

Not sure which grade fits your well or pipeline? Try our free AI pipe grade selector →

Supply Enquiry — Risers / Conductors

Tell us your grade, size, quantity, and delivery port. We will respond within one business day with availability and lead time.

Request a Quote

hazel.w@zcsteelpipe.com | WhatsApp +12132393018