1. Hoʻolauna

ASTM A333 Gr.6he mea paipu kila kalapona haʻahaʻa haʻahaʻa i hoʻohana nui ʻia, me ka mahana lawelawe haʻahaʻa loa o -45°C. Ma muli o kona paʻakikī haʻahaʻa haʻahaʻa maikaʻi loa a me ke kumukūʻai kūpono, hoʻohana nui ʻia ia i nā mea kanu petrochemical, nā lako cryogenic, a me nā ʻōnaehana hoʻoili kinoea liquefied.

Ma ke kūʻai ʻana o ka ʻenekinia,Nā paipu A333 Gr.6ua hoʻokaʻawale pinepine ʻia i ʻelua mau kūlana hoʻolako: "Sour Service" a me "Sweet Service" (maʻamau/maʻamau). ʻOiai ʻo nā ʻano ʻelua e hoʻokō i nā koi kemika kumu a me nā waiwai mechanical o ke kūlana ASTM A333, ʻokoʻa loa lākou i ko lākou kū'ē ʻana i ka hydrogen sulfide (H₂S) corrosion—he ʻokoʻa e hoʻoholo ai i kā lākou mau hiʻohiʻona noi like ʻole.

2. Nā ʻokoʻa koʻikoʻi ma waena o ka lawelawe ʻawaʻawa a me ka lawelawe ʻono

2.1 Nā Kūlana Lawelawe

ʻOno Lawelawe (ʻAʻohe ʻawaʻawa): Kūpono no nā wahi me ka ʻole o ka H₂S a i ʻole me ke kaomi hapa H₂S haʻahaʻa loa. ʻO nā mea nui e noʻonoʻo ai i ka hoʻolālā ʻana, ʻo ia ka paʻakikī o ka mahana haʻahaʻa a me ka hiki ke lawe i ke kaomi maʻamau.

Lawelawe ʻawaʻawa: Hoʻolālā kūikawā ʻia no nā wahi i loaʻa ka H₂S pulu, kahi e pono ai ka mea e kū i nā mahana haʻahaʻa a me ka pala H₂S i ka manawa like. Ua ʻae piha ʻia nā mea lawelawe ʻawaʻawa no nā noi lawelawe ʻono.

2.2 Ka Mana Hoʻohui Kemika

ʻOiai ke kuhikuhi kumu ASTM A333 Gr.6 e hoʻonohonoho ana i nā palena no C, Mn, P, S, a me nā mea ʻē aʻe, pono nā paipu lawelawe ʻawaʻawa i ka kaohi kemika paʻa loa:

Palena	Maʻamau A333 Gr.6	ʻO ka lawelawe ʻawaʻawa A333 Gr.6
Sulfur (S)	≤ 0.035%	Kāohi pono ʻia, maʻamau ≤ 0.015%
ʻO ka phosphorus (P)	≤ 0.035%	Kāohi pono ʻia, maʻamau ≤ 0.025%
Ka like o ke kalapona (CE)	ʻAʻole koi ʻia	Palena paʻa (e laʻa, ≤ 0.43%) e pale aku i ka paʻakikī nui

Ma ka hoʻēmi hou ʻana i nā mea haumia e like me S a me P, a me ka kaupalena ʻana i ke kalapona like, hoʻēmi nā paipu lawelawe ʻawaʻawa i ka hiki ke loaʻa i ka sulfide stress corrosion cracking (SSC) mai ka ʻike ʻana i ka haku mele kemika.

2.3 Nā Koina Paʻakikī a me ka Hoʻomehana

ʻO ke kāohi ʻana i ka paʻakikī kekahi o nā mea ʻokoʻa koʻikoʻi ma waena o ka lawelawe ʻawaʻawa a me ka lawelawe ʻono. Pono ka lawelawe ʻawaʻawa A333 Gr.6 i ka paʻakikī kiʻekiʻe o 22 HRC (Rockwell C) a i ʻole 248 HBW. ʻO kēia no ka mea he maʻalahi loa nā microstructures paʻakikī kiʻekiʻe i ka embrittlement i hoʻokomo ʻia e ka hydrogen a me ka stress corrosion cracking ma nā wahi H₂S.

E pili ana i ka mālama wela, koi pinepine nā paipu lawelawe ʻawaʻawa i nā kaʻina hana Normalized a Quenched & Tempered (Q&T) e hoʻokō ai i kahi microstructure like a maikaʻi hoʻi e hoʻonui ai i ke kū'ē ʻana o SSC. Loaʻa i nā paipu lawelawe maʻamau (ʻono) nā koi mālama wela i hoʻomaha ʻia.

2.4 Nā Koina Hoʻāʻo Hou Aʻe

Pono nā paipu lawelawe ʻawaʻawa e hōʻoia i ka hoʻokō ʻana maʻamau NACE (e laʻa, NACE MR0175 / ISO 15156), ʻo ia hoʻi:

Hoʻāʻo SSC (Sulfide Stress Cracking, NACE TM0177)

Hoʻāʻo HIC (Haki ʻia e ka Hydrogen, NACE TM0284)

ʻO ka maʻamau, pono nā paipu lawelawe maʻamau (ʻono) e hoʻokō i nā koi hoʻāʻo hopena haʻahaʻa o ASTM A333 (-46°C, ka awelika o ka ikehu hopena ≥ 20J) me ka hōʻoia ʻana o ka waiwai mechanical maʻamau.

3. Hōʻuluʻulu Manaʻo a me nā Manaʻo Koho

ʻAno	Maʻamau A333 Gr.6	ʻO ka lawelawe ʻawaʻawa A333 Gr.6
Waena lawelawe	ʻAʻohe H₂S a i ʻole H₂S liʻiliʻi	ʻO ka pāpaho ʻawaʻawa i loaʻa ka H₂S pulu
Palena Paʻakikī	ʻAʻohe kapu kūikawā	≤ 22 HRC / 248 HBW
Ka Lapaʻau Wela	Ka hana kuʻuna	ʻAno like o ka microstructure maʻamau a i ʻole Q&T
Hoʻāʻo Hou Aʻe	Hoʻāʻo hopena haʻahaʻa haʻahaʻa	Hoʻāʻo SSC + HIC e like me nā kūlana NACE
Hoʻokō NACE	ʻAʻole koi ʻia	Kūpono me NACE MR0175

Nā Manaʻo Koho: I ka wā o ka hoʻolālā ʻana, he mea nui e hoʻoholo inā aia ka H₂S i loko o ke kaiapuni lawelawe. Inā loaʻa nā kūlana H₂S pulu, pono e ʻōlelo maopopo ka kikoʻī o ke kūʻai ʻana "A333 Gr.6 no ka lawelawe ʻawaʻawa, kūlike me NACE MR0175 / ISO 15156," me nā koi kikoʻī no ka paʻakikī, ke kūlike kalapona, ka mālama wela, a me nā hoʻāʻo pākuʻi. ʻAʻole pono e hoʻohana ʻia nā paipu maʻamau A333 Gr.6 i nā mea ʻawaʻawa, no ka mea hiki i kēia ke alakaʻi i nā hemahema o ka haki ʻana o ka corrosion stress.